FreeBSD/Linux Kernel Cross Reference
sys/kern/subr_autoconf.c

     /* $NetBSD: subr_autoconf.c,v 1.306 2022/09/13 09:43:33 riastradh Exp $ */
     
     /*
      * Copyright (c) 1996, 2000 Christopher G. Demetriou
      * All rights reserved.
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
      * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 3. All advertising materials mentioning features or use of this software
     *    must display the following acknowledgement:
     *          This product includes software developed for the
     *          NetBSD Project.  See http://www.NetBSD.org/ for
     *          information about NetBSD.
     * 4. The name of the author may not be used to endorse or promote products
     *    derived from this software without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     *
     * --(license Id: LICENSE.proto,v 1.1 2000/06/13 21:40:26 cgd Exp )--
     */
    
    /*
     * Copyright (c) 1992, 1993
     *      The Regents of the University of California.  All rights reserved.
     *
     * This software was developed by the Computer Systems Engineering group
     * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
     * contributed to Berkeley.
     *
     * All advertising materials mentioning features or use of this software
     * must display the following acknowledgement:
     *      This product includes software developed by the University of
     *      California, Lawrence Berkeley Laboratories.
     *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 3. Neither the name of the University nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     * from: Header: subr_autoconf.c,v 1.12 93/02/01 19:31:48 torek Exp  (LBL)
     *
     *      @(#)subr_autoconf.c     8.3 (Berkeley) 5/17/94
     */
    
    #include <sys/cdefs.h>
    __KERNEL_RCSID(0, "$NetBSD: subr_autoconf.c,v 1.306 2022/09/13 09:43:33 riastradh Exp $");
    
    #ifdef _KERNEL_OPT
    #include "opt_ddb.h"
    #include "drvctl.h"
    #endif
    
    #include <sys/param.h>
    #include <sys/device.h>
    #include <sys/device_impl.h>
    #include <sys/disklabel.h>
    #include <sys/conf.h>
    #include <sys/kauth.h>
    #include <sys/kmem.h>
    #include <sys/systm.h>
    #include <sys/kernel.h>
    #include <sys/errno.h>
    #include <sys/proc.h>
    #include <sys/reboot.h>
    #include <sys/kthread.h>
   #include <sys/buf.h>
   #include <sys/dirent.h>
   #include <sys/mount.h>
   #include <sys/namei.h>
   #include <sys/unistd.h>
   #include <sys/fcntl.h>
   #include <sys/lockf.h>
   #include <sys/callout.h>
   #include <sys/devmon.h>
   #include <sys/cpu.h>
   #include <sys/sysctl.h>
   #include <sys/stdarg.h>
   #include <sys/localcount.h>
   
   #include <sys/disk.h>
   
   #include <sys/rndsource.h>
   
   #include <machine/limits.h>
   
   /*
    * Autoconfiguration subroutines.
    */
   
   /*
    * Device autoconfiguration timings are mixed into the entropy pool.
    */
   static krndsource_t rnd_autoconf_source;
   
   /*
    * ioconf.c exports exactly two names: cfdata and cfroots.  All system
    * devices and drivers are found via these tables.
    */
   extern struct cfdata cfdata[];
   extern const short cfroots[];
   
   /*
    * List of all cfdriver structures.  We use this to detect duplicates
    * when other cfdrivers are loaded.
    */
   struct cfdriverlist allcfdrivers = LIST_HEAD_INITIALIZER(&allcfdrivers);
   extern struct cfdriver * const cfdriver_list_initial[];
   
   /*
    * Initial list of cfattach's.
    */
   extern const struct cfattachinit cfattachinit[];
   
   /*
    * List of cfdata tables.  We always have one such list -- the one
    * built statically when the kernel was configured.
    */
   struct cftablelist allcftables = TAILQ_HEAD_INITIALIZER(allcftables);
   static struct cftable initcftable;
   
   #define ROOT ((device_t)NULL)
   
   struct matchinfo {
           cfsubmatch_t fn;
           device_t parent;
           const int *locs;
           void    *aux;
           struct  cfdata *match;
           int     pri;
   };
   
   struct alldevs_foray {
           int                     af_s;
           struct devicelist       af_garbage;
   };
   
   /*
    * Internal version of the cfargs structure; all versions are
    * canonicalized to this.
    */
   struct cfargs_internal {
           union {
                   cfsubmatch_t    submatch;/* submatch function (direct config) */
                   cfsearch_t      search;  /* search function (indirect config) */
           };
           const char *    iattr;          /* interface attribute */
           const int *     locators;       /* locators array */
           devhandle_t     devhandle;      /* devhandle_t (by value) */
   };
   
   static char *number(char *, int);
   static void mapply(struct matchinfo *, cfdata_t);
   static void config_devdelete(device_t);
   static void config_devunlink(device_t, struct devicelist *);
   static void config_makeroom(int, struct cfdriver *);
   static void config_devlink(device_t);
   static void config_alldevs_enter(struct alldevs_foray *);
   static void config_alldevs_exit(struct alldevs_foray *);
   static void config_add_attrib_dict(device_t);
   static device_t config_attach_internal(device_t, cfdata_t, void *,
                       cfprint_t, const struct cfargs_internal *);
   
   static void config_collect_garbage(struct devicelist *);
   static void config_dump_garbage(struct devicelist *);
   
   static void pmflock_debug(device_t, const char *, int);
   
   static device_t deviter_next1(deviter_t *);
   static void deviter_reinit(deviter_t *);
   
   struct deferred_config {
           TAILQ_ENTRY(deferred_config) dc_queue;
           device_t dc_dev;
           void (*dc_func)(device_t);
   };
   
   TAILQ_HEAD(deferred_config_head, deferred_config);
   
   static struct deferred_config_head deferred_config_queue =
           TAILQ_HEAD_INITIALIZER(deferred_config_queue);
   static struct deferred_config_head interrupt_config_queue =
           TAILQ_HEAD_INITIALIZER(interrupt_config_queue);
   static int interrupt_config_threads = 8;
   static struct deferred_config_head mountroot_config_queue =
           TAILQ_HEAD_INITIALIZER(mountroot_config_queue);
   static int mountroot_config_threads = 2;
   static lwp_t **mountroot_config_lwpids;
   static size_t mountroot_config_lwpids_size;
   bool root_is_mounted = false;
   
   static void config_process_deferred(struct deferred_config_head *, device_t);
   
   /* Hooks to finalize configuration once all real devices have been found. */
   struct finalize_hook {
           TAILQ_ENTRY(finalize_hook) f_list;
           int (*f_func)(device_t);
           device_t f_dev;
   };
   static TAILQ_HEAD(, finalize_hook) config_finalize_list =
           TAILQ_HEAD_INITIALIZER(config_finalize_list);
   static int config_finalize_done;
   
   /* list of all devices */
   static struct devicelist alldevs = TAILQ_HEAD_INITIALIZER(alldevs);
   static kmutex_t alldevs_lock __cacheline_aligned;
   static devgen_t alldevs_gen = 1;
   static int alldevs_nread = 0;
   static int alldevs_nwrite = 0;
   static bool alldevs_garbage = false;
   
   static struct devicelist config_pending =
       TAILQ_HEAD_INITIALIZER(config_pending);
   static kmutex_t config_misc_lock;
   static kcondvar_t config_misc_cv;
   
   static bool detachall = false;
   
   #define STREQ(s1, s2)                   \
           (*(s1) == *(s2) && strcmp((s1), (s2)) == 0)
   
   static bool config_initialized = false; /* config_init() has been called. */
   
   static int config_do_twiddle;
   static callout_t config_twiddle_ch;
   
   static void sysctl_detach_setup(struct sysctllog **);
   
   int no_devmon_insert(const char *, prop_dictionary_t);
   int (*devmon_insert_vec)(const char *, prop_dictionary_t) = no_devmon_insert;
   
   typedef int (*cfdriver_fn)(struct cfdriver *);
   static int
   frob_cfdrivervec(struct cfdriver * const *cfdriverv,
           cfdriver_fn drv_do, cfdriver_fn drv_undo,
           const char *style, bool dopanic)
   {
           void (*pr)(const char *, ...) __printflike(1, 2) =
               dopanic ? panic : printf;
           int i, error = 0, e2 __diagused;
   
           for (i = 0; cfdriverv[i] != NULL; i++) {
                   if ((error = drv_do(cfdriverv[i])) != 0) {
                           pr("configure: `%s' driver %s failed: %d",
                               cfdriverv[i]->cd_name, style, error);
                           goto bad;
                   }
           }
   
           KASSERT(error == 0);
           return 0;
   
    bad:
           printf("\n");
           for (i--; i >= 0; i--) {
                   e2 = drv_undo(cfdriverv[i]);
                   KASSERT(e2 == 0);
           }
   
           return error;
   }
   
   typedef int (*cfattach_fn)(const char *, struct cfattach *);
   static int
   frob_cfattachvec(const struct cfattachinit *cfattachv,
           cfattach_fn att_do, cfattach_fn att_undo,
           const char *style, bool dopanic)
   {
           const struct cfattachinit *cfai = NULL;
           void (*pr)(const char *, ...) __printflike(1, 2) =
               dopanic ? panic : printf;
           int j = 0, error = 0, e2 __diagused;
   
           for (cfai = &cfattachv[0]; cfai->cfai_name != NULL; cfai++) {
                   for (j = 0; cfai->cfai_list[j] != NULL; j++) {
                           if ((error = att_do(cfai->cfai_name,
                               cfai->cfai_list[j])) != 0) {
                                   pr("configure: attachment `%s' "
                                       "of `%s' driver %s failed: %d",
                                       cfai->cfai_list[j]->ca_name,
                                       cfai->cfai_name, style, error);
                                   goto bad;
                           }
                   }
           }
   
           KASSERT(error == 0);
           return 0;
   
    bad:
           /*
            * Rollback in reverse order.  dunno if super-important, but
            * do that anyway.  Although the code looks a little like
            * someone did a little integration (in the math sense).
            */
           printf("\n");
           if (cfai) {
                   bool last;
   
                   for (last = false; last == false; ) {
                           if (cfai == &cfattachv[0])
                                   last = true;
                           for (j--; j >= 0; j--) {
                                   e2 = att_undo(cfai->cfai_name,
                                       cfai->cfai_list[j]);
                                   KASSERT(e2 == 0);
                           }
                           if (!last) {
                                   cfai--;
                                   for (j = 0; cfai->cfai_list[j] != NULL; j++)
                                           ;
                           }
                   }
           }
   
           return error;
   }
   
   /*
    * Initialize the autoconfiguration data structures.  Normally this
    * is done by configure(), but some platforms need to do this very
    * early (to e.g. initialize the console).
    */
   void
   config_init(void)
   {
   
           KASSERT(config_initialized == false);
   
           mutex_init(&alldevs_lock, MUTEX_DEFAULT, IPL_VM);
   
           mutex_init(&config_misc_lock, MUTEX_DEFAULT, IPL_NONE);
           cv_init(&config_misc_cv, "cfgmisc");
   
           callout_init(&config_twiddle_ch, CALLOUT_MPSAFE);
   
           frob_cfdrivervec(cfdriver_list_initial,
               config_cfdriver_attach, NULL, "bootstrap", true);
           frob_cfattachvec(cfattachinit,
               config_cfattach_attach, NULL, "bootstrap", true);
   
           initcftable.ct_cfdata = cfdata;
           TAILQ_INSERT_TAIL(&allcftables, &initcftable, ct_list);
   
           rnd_attach_source(&rnd_autoconf_source, "autoconf", RND_TYPE_UNKNOWN,
               RND_FLAG_COLLECT_TIME);
   
           config_initialized = true;
   }
   
   /*
    * Init or fini drivers and attachments.  Either all or none
    * are processed (via rollback).  It would be nice if this were
    * atomic to outside consumers, but with the current state of
    * locking ...
    */
   int
   config_init_component(struct cfdriver * const *cfdriverv,
           const struct cfattachinit *cfattachv, struct cfdata *cfdatav)
   {
           int error;
   
           KERNEL_LOCK(1, NULL);
   
           if ((error = frob_cfdrivervec(cfdriverv,
               config_cfdriver_attach, config_cfdriver_detach, "init", false))!= 0)
                   goto out;
           if ((error = frob_cfattachvec(cfattachv,
               config_cfattach_attach, config_cfattach_detach,
               "init", false)) != 0) {
                   frob_cfdrivervec(cfdriverv,
                       config_cfdriver_detach, NULL, "init rollback", true);
                   goto out;
           }
           if ((error = config_cfdata_attach(cfdatav, 1)) != 0) {
                   frob_cfattachvec(cfattachv,
                       config_cfattach_detach, NULL, "init rollback", true);
                   frob_cfdrivervec(cfdriverv,
                       config_cfdriver_detach, NULL, "init rollback", true);
                   goto out;
           }
   
           /* Success!  */
           error = 0;
   
   out:    KERNEL_UNLOCK_ONE(NULL);
           return error;
   }
   
   int
   config_fini_component(struct cfdriver * const *cfdriverv,
           const struct cfattachinit *cfattachv, struct cfdata *cfdatav)
   {
           int error;
   
           KERNEL_LOCK(1, NULL);
   
           if ((error = config_cfdata_detach(cfdatav)) != 0)
                   goto out;
           if ((error = frob_cfattachvec(cfattachv,
               config_cfattach_detach, config_cfattach_attach,
               "fini", false)) != 0) {
                   if (config_cfdata_attach(cfdatav, 0) != 0)
                           panic("config_cfdata fini rollback failed");
                   goto out;
           }
           if ((error = frob_cfdrivervec(cfdriverv,
               config_cfdriver_detach, config_cfdriver_attach,
               "fini", false)) != 0) {
                   frob_cfattachvec(cfattachv,
                       config_cfattach_attach, NULL, "fini rollback", true);
                   if (config_cfdata_attach(cfdatav, 0) != 0)
                           panic("config_cfdata fini rollback failed");
                   goto out;
           }
   
           /* Success!  */
           error = 0;
   
   out:    KERNEL_UNLOCK_ONE(NULL);
           return error;
   }
   
   void
   config_init_mi(void)
   {
   
           if (!config_initialized)
                   config_init();
   
           sysctl_detach_setup(NULL);
   }
   
   void
   config_deferred(device_t dev)
   {
   
           KASSERT(KERNEL_LOCKED_P());
   
           config_process_deferred(&deferred_config_queue, dev);
           config_process_deferred(&interrupt_config_queue, dev);
           config_process_deferred(&mountroot_config_queue, dev);
   }
   
   static void
   config_interrupts_thread(void *cookie)
   {
           struct deferred_config *dc;
           device_t dev;
   
           mutex_enter(&config_misc_lock);
           while ((dc = TAILQ_FIRST(&interrupt_config_queue)) != NULL) {
                   TAILQ_REMOVE(&interrupt_config_queue, dc, dc_queue);
                   mutex_exit(&config_misc_lock);
   
                   dev = dc->dc_dev;
                   (*dc->dc_func)(dev);
                   if (!device_pmf_is_registered(dev))
                           aprint_debug_dev(dev,
                               "WARNING: power management not supported\n");
                   config_pending_decr(dev);
                   kmem_free(dc, sizeof(*dc));
   
                   mutex_enter(&config_misc_lock);
           }
           mutex_exit(&config_misc_lock);
   
           kthread_exit(0);
   }
   
   void
   config_create_interruptthreads(void)
   {
           int i;
   
           for (i = 0; i < interrupt_config_threads; i++) {
                   (void)kthread_create(PRI_NONE, 0/*XXXSMP */, NULL,
                       config_interrupts_thread, NULL, NULL, "configintr");
           }
   }
   
   static void
   config_mountroot_thread(void *cookie)
   {
           struct deferred_config *dc;
   
           mutex_enter(&config_misc_lock);
           while ((dc = TAILQ_FIRST(&mountroot_config_queue)) != NULL) {
                   TAILQ_REMOVE(&mountroot_config_queue, dc, dc_queue);
                   mutex_exit(&config_misc_lock);
   
                   (*dc->dc_func)(dc->dc_dev);
                   kmem_free(dc, sizeof(*dc));
   
                   mutex_enter(&config_misc_lock);
           }
           mutex_exit(&config_misc_lock);
   
           kthread_exit(0);
   }
   
   void
   config_create_mountrootthreads(void)
   {
           int i;
   
           if (!root_is_mounted)
                   root_is_mounted = true;
   
           mountroot_config_lwpids_size = sizeof(mountroot_config_lwpids) *
                                          mountroot_config_threads;
           mountroot_config_lwpids = kmem_alloc(mountroot_config_lwpids_size,
                                                KM_NOSLEEP);
           KASSERT(mountroot_config_lwpids);
           for (i = 0; i < mountroot_config_threads; i++) {
                   mountroot_config_lwpids[i] = 0;
                   (void)kthread_create(PRI_NONE, KTHREAD_MUSTJOIN/* XXXSMP */,
                                        NULL, config_mountroot_thread, NULL,
                                        &mountroot_config_lwpids[i],
                                        "configroot");
           }
   }
   
   void
   config_finalize_mountroot(void)
   {
           int i, error;
   
           for (i = 0; i < mountroot_config_threads; i++) {
                   if (mountroot_config_lwpids[i] == 0)
                           continue;
   
                   error = kthread_join(mountroot_config_lwpids[i]);
                   if (error)
                           printf("%s: thread %x joined with error %d\n",
                                  __func__, i, error);
           }
           kmem_free(mountroot_config_lwpids, mountroot_config_lwpids_size);
   }
   
   /*
    * Announce device attach/detach to userland listeners.
    */
   
   int
   no_devmon_insert(const char *name, prop_dictionary_t p)
   {
   
           return ENODEV;
   }
   
   static void
   devmon_report_device(device_t dev, bool isattach)
   {
           prop_dictionary_t ev, dict = device_properties(dev);
           const char *parent;
           const char *what;
           const char *where;
           device_t pdev = device_parent(dev);
   
           /* If currently no drvctl device, just return */
           if (devmon_insert_vec == no_devmon_insert)
                   return;
   
           ev = prop_dictionary_create();
           if (ev == NULL)
                   return;
   
           what = (isattach ? "device-attach" : "device-detach");
           parent = (pdev == NULL ? "root" : device_xname(pdev));
           if (prop_dictionary_get_string(dict, "location", &where)) {
                   prop_dictionary_set_string(ev, "location", where);
                   aprint_debug("ev: %s %s at %s in [%s]\n",
                       what, device_xname(dev), parent, where); 
           }
           if (!prop_dictionary_set_string(ev, "device", device_xname(dev)) ||
               !prop_dictionary_set_string(ev, "parent", parent)) {
                   prop_object_release(ev);
                   return;
           }
   
           if ((*devmon_insert_vec)(what, ev) != 0)
                   prop_object_release(ev);
   }
   
   /*
    * Add a cfdriver to the system.
    */
   int
   config_cfdriver_attach(struct cfdriver *cd)
   {
           struct cfdriver *lcd;
   
           /* Make sure this driver isn't already in the system. */
           LIST_FOREACH(lcd, &allcfdrivers, cd_list) {
                   if (STREQ(lcd->cd_name, cd->cd_name))
                           return EEXIST;
           }
   
           LIST_INIT(&cd->cd_attach);
           LIST_INSERT_HEAD(&allcfdrivers, cd, cd_list);
   
           return 0;
   }
   
   /*
    * Remove a cfdriver from the system.
    */
   int
   config_cfdriver_detach(struct cfdriver *cd)
   {
           struct alldevs_foray af;
           int i, rc = 0;
   
           config_alldevs_enter(&af);
           /* Make sure there are no active instances. */
           for (i = 0; i < cd->cd_ndevs; i++) {
                   if (cd->cd_devs[i] != NULL) {
                           rc = EBUSY;
                           break;
                   }
           }
           config_alldevs_exit(&af);
   
           if (rc != 0)
                   return rc;
   
           /* ...and no attachments loaded. */
           if (LIST_EMPTY(&cd->cd_attach) == 0)
                   return EBUSY;
   
           LIST_REMOVE(cd, cd_list);
   
           KASSERT(cd->cd_devs == NULL);
   
           return 0;
   }
   
   /*
    * Look up a cfdriver by name.
    */
   struct cfdriver *
   config_cfdriver_lookup(const char *name)
   {
           struct cfdriver *cd;
   
           LIST_FOREACH(cd, &allcfdrivers, cd_list) {
                   if (STREQ(cd->cd_name, name))
                           return cd;
           }
   
           return NULL;
   }
   
   /*
    * Add a cfattach to the specified driver.
    */
   int
   config_cfattach_attach(const char *driver, struct cfattach *ca)
   {
           struct cfattach *lca;
           struct cfdriver *cd;
   
           cd = config_cfdriver_lookup(driver);
           if (cd == NULL)
                   return ESRCH;
   
           /* Make sure this attachment isn't already on this driver. */
           LIST_FOREACH(lca, &cd->cd_attach, ca_list) {
                   if (STREQ(lca->ca_name, ca->ca_name))
                           return EEXIST;
           }
   
           LIST_INSERT_HEAD(&cd->cd_attach, ca, ca_list);
   
           return 0;
   }
   
   /*
    * Remove a cfattach from the specified driver.
    */
   int
   config_cfattach_detach(const char *driver, struct cfattach *ca)
   {
           struct alldevs_foray af;
           struct cfdriver *cd;
           device_t dev;
           int i, rc = 0;
   
           cd = config_cfdriver_lookup(driver);
           if (cd == NULL)
                   return ESRCH;
   
           config_alldevs_enter(&af);
           /* Make sure there are no active instances. */
           for (i = 0; i < cd->cd_ndevs; i++) {
                   if ((dev = cd->cd_devs[i]) == NULL)
                           continue;
                   if (dev->dv_cfattach == ca) {
                           rc = EBUSY;
                           break;
                   }
           }
           config_alldevs_exit(&af);
   
           if (rc != 0)
                   return rc;
   
           LIST_REMOVE(ca, ca_list);
   
           return 0;
   }
   
   /*
    * Look up a cfattach by name.
    */
   static struct cfattach *
   config_cfattach_lookup_cd(struct cfdriver *cd, const char *atname)
   {
           struct cfattach *ca;
   
           LIST_FOREACH(ca, &cd->cd_attach, ca_list) {
                   if (STREQ(ca->ca_name, atname))
                           return ca;
           }
   
           return NULL;
   }
   
   /*
    * Look up a cfattach by driver/attachment name.
    */
   struct cfattach *
   config_cfattach_lookup(const char *name, const char *atname)
   {
           struct cfdriver *cd;
   
           cd = config_cfdriver_lookup(name);
           if (cd == NULL)
                   return NULL;
   
           return config_cfattach_lookup_cd(cd, atname);
   }
   
   /*
    * Apply the matching function and choose the best.  This is used
    * a few times and we want to keep the code small.
    */
   static void
   mapply(struct matchinfo *m, cfdata_t cf)
   {
           int pri;
   
           if (m->fn != NULL) {
                   pri = (*m->fn)(m->parent, cf, m->locs, m->aux);
           } else {
                   pri = config_match(m->parent, cf, m->aux);
           }
           if (pri > m->pri) {
                   m->match = cf;
                   m->pri = pri;
           }
   }
   
   int
   config_stdsubmatch(device_t parent, cfdata_t cf, const int *locs, void *aux)
   {
           const struct cfiattrdata *ci;
           const struct cflocdesc *cl;
           int nlocs, i;
   
           ci = cfiattr_lookup(cfdata_ifattr(cf), parent->dv_cfdriver);
           KASSERT(ci);
           nlocs = ci->ci_loclen;
           KASSERT(!nlocs || locs);
           for (i = 0; i < nlocs; i++) {
                   cl = &ci->ci_locdesc[i];
                   if (cl->cld_defaultstr != NULL &&
                       cf->cf_loc[i] == cl->cld_default)
                           continue;
                   if (cf->cf_loc[i] == locs[i])
                           continue;
                   return 0;
           }
   
           return config_match(parent, cf, aux);
   }
   
   /*
    * Helper function: check whether the driver supports the interface attribute
    * and return its descriptor structure.
    */
   static const struct cfiattrdata *
   cfdriver_get_iattr(const struct cfdriver *cd, const char *ia)
   {
           const struct cfiattrdata * const *cpp;
   
           if (cd->cd_attrs == NULL)
                   return 0;
   
           for (cpp = cd->cd_attrs; *cpp; cpp++) {
                   if (STREQ((*cpp)->ci_name, ia)) {
                           /* Match. */
                           return *cpp;
                   }
           }
           return 0;
   }
   
   static int __diagused
   cfdriver_iattr_count(const struct cfdriver *cd)
   {
           const struct cfiattrdata * const *cpp;
           int i;
   
           if (cd->cd_attrs == NULL)
                   return 0;
   
           for (i = 0, cpp = cd->cd_attrs; *cpp; cpp++) {
                   i++;
           }
           return i;
   }
   
   /*
    * Lookup an interface attribute description by name.
    * If the driver is given, consider only its supported attributes.
    */
   const struct cfiattrdata *
   cfiattr_lookup(const char *name, const struct cfdriver *cd)
   {
           const struct cfdriver *d;
           const struct cfiattrdata *ia;
   
           if (cd)
                   return cfdriver_get_iattr(cd, name);
   
           LIST_FOREACH(d, &allcfdrivers, cd_list) {
                   ia = cfdriver_get_iattr(d, name);
                   if (ia)
                           return ia;
           }
           return 0;
   }
   
   /*
    * Determine if `parent' is a potential parent for a device spec based
    * on `cfp'.
    */
   static int
   cfparent_match(const device_t parent, const struct cfparent *cfp)
   {
           struct cfdriver *pcd;
   
           /* We don't match root nodes here. */
           if (cfp == NULL)
                   return 0;
   
           pcd = parent->dv_cfdriver;
           KASSERT(pcd != NULL);
   
           /*
            * First, ensure this parent has the correct interface
            * attribute.
            */
           if (!cfdriver_get_iattr(pcd, cfp->cfp_iattr))
                   return 0;
   
           /*
            * If no specific parent device instance was specified (i.e.
            * we're attaching to the attribute only), we're done!
            */
           if (cfp->cfp_parent == NULL)
                   return 1;
   
           /*
            * Check the parent device's name.
            */
           if (STREQ(pcd->cd_name, cfp->cfp_parent) == 0)
                   return 0;       /* not the same parent */
   
           /*
            * Make sure the unit number matches.
            */
           if (cfp->cfp_unit == DVUNIT_ANY ||      /* wildcard */
               cfp->cfp_unit == parent->dv_unit)
                   return 1;
   
           /* Unit numbers don't match. */
           return 0;
   }
   
   /*
    * Helper for config_cfdata_attach(): check all devices whether it could be
    * parent any attachment in the config data table passed, and rescan.
    */
   static void
   rescan_with_cfdata(const struct cfdata *cf)
   {
           device_t d;
           const struct cfdata *cf1;
           deviter_t di;
   
           KASSERT(KERNEL_LOCKED_P());
   
           /*
            * "alldevs" is likely longer than a modules's cfdata, so make it
            * the outer loop.
            */
           for (d = deviter_first(&di, 0); d != NULL; d = deviter_next(&di)) {
   
                   if (!(d->dv_cfattach->ca_rescan))
                           continue;
   
                   for (cf1 = cf; cf1->cf_name; cf1++) {
   
                           if (!cfparent_match(d, cf1->cf_pspec))
                                   continue;
   
                           (*d->dv_cfattach->ca_rescan)(d,
                                   cfdata_ifattr(cf1), cf1->cf_loc);
   
                           config_deferred(d);
                   }
           }
           deviter_release(&di);
   }
   
   /*
    * Attach a supplemental config data table and rescan potential
    * parent devices if required.
    */
   int
   config_cfdata_attach(cfdata_t cf, int scannow)
   {
           struct cftable *ct;
   
           KERNEL_LOCK(1, NULL);
   
           ct = kmem_alloc(sizeof(*ct), KM_SLEEP);
           ct->ct_cfdata = cf;
           TAILQ_INSERT_TAIL(&allcftables, ct, ct_list);
   
           if (scannow)
                   rescan_with_cfdata(cf);
   
           KERNEL_UNLOCK_ONE(NULL);
   
           return 0;
   }
   
   /*
    * Helper for config_cfdata_detach: check whether a device is
    * found through any attachment in the config data table.
    */
   static int
   dev_in_cfdata(device_t d, cfdata_t cf)
   {
           const struct cfdata *cf1;
   
           for (cf1 = cf; cf1->cf_name; cf1++)
                   if (d->dv_cfdata == cf1)
                           return 1;
   
           return 0;
   }
  
  /*
   * Detach a supplemental config data table. Detach all devices found
   * through that table (and thus keeping references to it) before.
   */
  int
  config_cfdata_detach(cfdata_t cf)
  {
          device_t d;
          int error = 0;
          struct cftable *ct;
          deviter_t di;
  
          KERNEL_LOCK(1, NULL);
  
          for (d = deviter_first(&di, DEVITER_F_RW); d != NULL;
               d = deviter_next(&di)) {
                  if (!dev_in_cfdata(d, cf))
                          continue;
                  if ((error = config_detach(d, 0)) != 0)
                          break;
          }
          deviter_release(&di);
          if (error) {
                  aprint_error_dev(d, "unable to detach instance\n");
                  goto out;
          }
  
          TAILQ_FOREACH(ct, &allcftables, ct_list) {
                  if (ct->ct_cfdata == cf) {
                          TAILQ_REMOVE(&allcftables, ct, ct_list);
                          kmem_free(ct, sizeof(*ct));
                          error = 0;
                          goto out;
                  }
          }
  
          /* not found -- shouldn't happen */
          error = EINVAL;
  
  out:    KERNEL_UNLOCK_ONE(NULL);
          return error;
  }
  
  /*
   * Invoke the "match" routine for a cfdata entry on behalf of
   * an external caller, usually a direct config "submatch" routine.
   */
  int
  config_match(device_t parent, cfdata_t cf, void *aux)
  {
          struct cfattach *ca;
  
          KASSERT(KERNEL_LOCKED_P());
  
          ca = config_cfattach_lookup(cf->cf_name, cf->cf_atname);
          if (ca == NULL) {
                  /* No attachment for this entry, oh well. */
                  return 0;
          }
  
          return (*ca->ca_match)(parent, cf, aux);
  }
  
  /*
   * Invoke the "probe" routine for a cfdata entry on behalf of
   * an external caller, usually an indirect config "search" routine.
   */
  int
  config_probe(device_t parent, cfdata_t cf, void *aux)
  {
          /*
           * This is currently a synonym for config_match(), but this
           * is an implementation detail; "match" and "probe" routines
           * have different behaviors.
           *
           * XXX config_probe() should return a bool, because there is
           * XXX no match score for probe -- it's either there or it's
           * XXX not, but some ports abuse the return value as a way
           * XXX to attach "critical" devices before "non-critical"
           * XXX devices.
           */
          return config_match(parent, cf, aux);
  }
  
  static struct cfargs_internal *
  cfargs_canonicalize(const struct cfargs * const cfargs,
      struct cfargs_internal * const store)
  {
          struct cfargs_internal *args = store;
  
          memset(args, 0, sizeof(*args));
  
          /* If none specified, are all-NULL pointers are good. */
          if (cfargs == NULL) {
                  return args;
          }
  
          /*
           * Only one arguments version is recognized at this time.
           */
          if (cfargs->cfargs_version != CFARGS_VERSION) {
                  panic("cfargs_canonicalize: unknown version %lu\n",
                      (unsigned long)cfargs->cfargs_version);
          }
  
          /*
           * submatch and search are mutually-exclusive.
           */
          if (cfargs->submatch != NULL && cfargs->search != NULL) {
                  panic("cfargs_canonicalize: submatch and search are "
                        "mutually-exclusive");
          }
          if (cfargs->submatch != NULL) {
                  args->submatch = cfargs->submatch;
          } else if (cfargs->search != NULL) {
                  args->search = cfargs->search;
          }
  
          args->iattr = cfargs->iattr;
          args->locators = cfargs->locators;
          args->devhandle = cfargs->devhandle;
  
          return args;
  }
  
  /*
   * Iterate over all potential children of some device, calling the given
   * function (default being the child's match function) for each one.
   * Nonzero returns are matches; the highest value returned is considered
   * the best match.  Return the `found child' if we got a match, or NULL
   * otherwise.  The `aux' pointer is simply passed on through.
   *
   * Note that this function is designed so that it can be used to apply
   * an arbitrary function to all potential children (its return value
   * can be ignored).
   */
  static cfdata_t
  config_search_internal(device_t parent, void *aux,
      const struct cfargs_internal * const args)
  {
          struct cftable *ct;
          cfdata_t cf;
          struct matchinfo m;
  
          KASSERT(config_initialized);
          KASSERT(!args->iattr ||
                  cfdriver_get_iattr(parent->dv_cfdriver, args->iattr));
          KASSERT(args->iattr ||
                  cfdriver_iattr_count(parent->dv_cfdriver) < 2);
  
          m.fn = args->submatch;          /* N.B. union */
          m.parent = parent;
          m.locs = args->locators;
          m.aux = aux;
          m.match = NULL;
          m.pri = 0;
  
          TAILQ_FOREACH(ct, &allcftables, ct_list) {
                  for (cf = ct->ct_cfdata; cf->cf_name; cf++) {
  
                          /* We don't match root nodes here. */
                          if (!cf->cf_pspec)
                                  continue;
  
                          /*
                           * Skip cf if no longer eligible, otherwise scan
                           * through parents for one matching `parent', and
                           * try match function.
                           */
                          if (cf->cf_fstate == FSTATE_FOUND)
                                  continue;
                          if (cf->cf_fstate == FSTATE_DNOTFOUND ||
                              cf->cf_fstate == FSTATE_DSTAR)
                                  continue;
  
                          /*
                           * If an interface attribute was specified,
                           * consider only children which attach to
                           * that attribute.
                           */
                          if (args->iattr != NULL &&
                              !STREQ(args->iattr, cfdata_ifattr(cf)))
                                  continue;
  
                          if (cfparent_match(parent, cf->cf_pspec))
                                  mapply(&m, cf);
                  }
          }
          rnd_add_uint32(&rnd_autoconf_source, 0);
          return m.match;
  }
  
  cfdata_t
  config_search(device_t parent, void *aux, const struct cfargs *cfargs)
  {
          cfdata_t cf;
          struct cfargs_internal store;
  
          cf = config_search_internal(parent, aux,
              cfargs_canonicalize(cfargs, &store));
  
          return cf;
  }
  
  /*
   * Find the given root device.
   * This is much like config_search, but there is no parent.
   * Don't bother with multiple cfdata tables; the root node
   * must always be in the initial table.
   */
  cfdata_t
  config_rootsearch(cfsubmatch_t fn, const char *rootname, void *aux)
  {
          cfdata_t cf;
          const short *p;
          struct matchinfo m;
  
          m.fn = fn;
          m.parent = ROOT;
          m.aux = aux;
          m.match = NULL;
          m.pri = 0;
          m.locs = 0;
          /*
           * Look at root entries for matching name.  We do not bother
           * with found-state here since only one root should ever be
           * searched (and it must be done first).
           */
          for (p = cfroots; *p >= 0; p++) {
                  cf = &cfdata[*p];
                  if (strcmp(cf->cf_name, rootname) == 0)
                          mapply(&m, cf);
          }
          return m.match;
  }
  
  static const char * const msgs[] = {
  [QUIET]         =       "",
  [UNCONF]        =       " not configured\n",
  [UNSUPP]        =       " unsupported\n",
  };
  
  /*
   * The given `aux' argument describes a device that has been found
   * on the given parent, but not necessarily configured.  Locate the
   * configuration data for that device (using the submatch function
   * provided, or using candidates' cd_match configuration driver
   * functions) and attach it, and return its device_t.  If the device was
   * not configured, call the given `print' function and return NULL.
   */
  device_t
  config_found(device_t parent, void *aux, cfprint_t print,
      const struct cfargs * const cfargs)
  {
          cfdata_t cf;
          struct cfargs_internal store;
          const struct cfargs_internal * const args =
              cfargs_canonicalize(cfargs, &store);
  
          cf = config_search_internal(parent, aux, args);
          if (cf != NULL) {
                  return config_attach_internal(parent, cf, aux, print, args);
          }
  
          if (print) {
                  if (config_do_twiddle && cold)
                          twiddle();
  
                  const int pret = (*print)(aux, device_xname(parent));
                  KASSERT(pret >= 0);
                  KASSERT(pret < __arraycount(msgs));
                  KASSERT(msgs[pret] != NULL);
                  aprint_normal("%s", msgs[pret]);
          }
  
          return NULL;
  }
  
  /*
   * As above, but for root devices.
   */
  device_t
  config_rootfound(const char *rootname, void *aux)
  {
          cfdata_t cf;
          device_t dev = NULL;
  
          KERNEL_LOCK(1, NULL);
          if ((cf = config_rootsearch(NULL, rootname, aux)) != NULL)
                  dev = config_attach(ROOT, cf, aux, NULL, CFARGS_NONE);
          else
                  aprint_error("root device %s not configured\n", rootname);
          KERNEL_UNLOCK_ONE(NULL);
          return dev;
  }
  
  /* just like sprintf(buf, "%d") except that it works from the end */
  static char *
  number(char *ep, int n)
  {
  
          *--ep = 0;
          while (n >= 10) {
                  *--ep = (n % 10) + '';
                  n /= 10;
          }
          *--ep = n + '';
          return ep;
  }
  
  /*
   * Expand the size of the cd_devs array if necessary.
   *
   * The caller must hold alldevs_lock. config_makeroom() may release and
   * re-acquire alldevs_lock, so callers should re-check conditions such
   * as alldevs_nwrite == 0 and alldevs_nread == 0 when config_makeroom()
   * returns.
   */
  static void
  config_makeroom(int n, struct cfdriver *cd)
  {
          int ondevs, nndevs;
          device_t *osp, *nsp;
  
          KASSERT(mutex_owned(&alldevs_lock));
          alldevs_nwrite++;
  
          for (nndevs = MAX(4, cd->cd_ndevs); nndevs <= n; nndevs += nndevs)
                  ;
  
          while (n >= cd->cd_ndevs) {
                  /*
                   * Need to expand the array.
                   */
                  ondevs = cd->cd_ndevs;
                  osp = cd->cd_devs;
  
                  /*
                   * Release alldevs_lock around allocation, which may
                   * sleep.
                   */
                  mutex_exit(&alldevs_lock);
                  nsp = kmem_alloc(sizeof(device_t) * nndevs, KM_SLEEP);
                  mutex_enter(&alldevs_lock);
  
                  /*
                   * If another thread moved the array while we did
                   * not hold alldevs_lock, try again.
                   */
                  if (cd->cd_devs != osp) {
                          mutex_exit(&alldevs_lock);
                          kmem_free(nsp, sizeof(device_t) * nndevs);
                          mutex_enter(&alldevs_lock);
                          continue;
                  }
  
                  memset(nsp + ondevs, 0, sizeof(device_t) * (nndevs - ondevs));
                  if (ondevs != 0)
                          memcpy(nsp, cd->cd_devs, sizeof(device_t) * ondevs);
  
                  cd->cd_ndevs = nndevs;
                  cd->cd_devs = nsp;
                  if (ondevs != 0) {
                          mutex_exit(&alldevs_lock);
                          kmem_free(osp, sizeof(device_t) * ondevs);
                          mutex_enter(&alldevs_lock);
                  }
          }
          KASSERT(mutex_owned(&alldevs_lock));
          alldevs_nwrite--;
  }
  
  /*
   * Put dev into the devices list.
   */
  static void
  config_devlink(device_t dev)
  {
  
          mutex_enter(&alldevs_lock);
  
          KASSERT(device_cfdriver(dev)->cd_devs[dev->dv_unit] == dev);
  
          dev->dv_add_gen = alldevs_gen;
          /* It is safe to add a device to the tail of the list while
           * readers and writers are in the list.
           */
          TAILQ_INSERT_TAIL(&alldevs, dev, dv_list);
          mutex_exit(&alldevs_lock);
  }
  
  static void
  config_devfree(device_t dev)
  {
  
          KASSERT(dev->dv_flags & DVF_PRIV_ALLOC);
          KASSERTMSG(dev->dv_pending == 0, "%d", dev->dv_pending);
  
          if (dev->dv_cfattach->ca_devsize > 0)
                  kmem_free(dev->dv_private, dev->dv_cfattach->ca_devsize);
          kmem_free(dev, sizeof(*dev));
  }
  
  /*
   * Caller must hold alldevs_lock.
   */
  static void
  config_devunlink(device_t dev, struct devicelist *garbage)
  {
          struct device_garbage *dg = &dev->dv_garbage;
          cfdriver_t cd = device_cfdriver(dev);
          int i;
  
          KASSERT(mutex_owned(&alldevs_lock));
          KASSERTMSG(dev->dv_pending == 0, "%d", dev->dv_pending);
  
          /* Unlink from device list.  Link to garbage list. */
          TAILQ_REMOVE(&alldevs, dev, dv_list);
          TAILQ_INSERT_TAIL(garbage, dev, dv_list);
  
          /* Remove from cfdriver's array. */
          cd->cd_devs[dev->dv_unit] = NULL;
  
          /*
           * If the device now has no units in use, unlink its softc array.
           */
          for (i = 0; i < cd->cd_ndevs; i++) {
                  if (cd->cd_devs[i] != NULL)
                          break;
          }
          /* Nothing found.  Unlink, now.  Deallocate, later. */
          if (i == cd->cd_ndevs) {
                  dg->dg_ndevs = cd->cd_ndevs;
                  dg->dg_devs = cd->cd_devs;
                  cd->cd_devs = NULL;
                  cd->cd_ndevs = 0;
          }
  }
  
  static void
  config_devdelete(device_t dev)
  {
          struct device_garbage *dg = &dev->dv_garbage;
          device_lock_t dvl = device_getlock(dev);
  
          KASSERTMSG(dev->dv_pending == 0, "%d", dev->dv_pending);
  
          if (dg->dg_devs != NULL)
                  kmem_free(dg->dg_devs, sizeof(device_t) * dg->dg_ndevs);
  
          localcount_fini(dev->dv_localcount);
          kmem_free(dev->dv_localcount, sizeof(*dev->dv_localcount));
  
          cv_destroy(&dvl->dvl_cv);
          mutex_destroy(&dvl->dvl_mtx);
  
          KASSERT(dev->dv_properties != NULL);
          prop_object_release(dev->dv_properties);
  
          if (dev->dv_activity_handlers)
                  panic("%s with registered handlers", __func__);
  
          if (dev->dv_locators) {
                  size_t amount = *--dev->dv_locators;
                  kmem_free(dev->dv_locators, amount);
          }
  
          config_devfree(dev);
  }
  
  static int
  config_unit_nextfree(cfdriver_t cd, cfdata_t cf)
  {
          int unit = cf->cf_unit;
  
          if (unit < 0)
                  return -1;
          if (cf->cf_fstate == FSTATE_STAR) {
                  for (; unit < cd->cd_ndevs; unit++)
                          if (cd->cd_devs[unit] == NULL)
                                  break;
                  /*
                   * unit is now the unit of the first NULL device pointer,
                   * or max(cd->cd_ndevs,cf->cf_unit).
                   */
          } else {
                  if (unit < cd->cd_ndevs && cd->cd_devs[unit] != NULL)
                          unit = -1;
          }
          return unit;
  }
  
  static int
  config_unit_alloc(device_t dev, cfdriver_t cd, cfdata_t cf)
  {
          struct alldevs_foray af;
          int unit;
  
          config_alldevs_enter(&af);
          for (;;) {
                  unit = config_unit_nextfree(cd, cf);
                  if (unit == -1)
                          break;
                  if (unit < cd->cd_ndevs) {
                          cd->cd_devs[unit] = dev;
                          dev->dv_unit = unit;
                          break;
                  }
                  config_makeroom(unit, cd);
          }
          config_alldevs_exit(&af);
  
          return unit;
  }
  
  static device_t
  config_devalloc(const device_t parent, const cfdata_t cf,
      const struct cfargs_internal * const args)
  {
          cfdriver_t cd;
          cfattach_t ca;
          size_t lname, lunit;
          const char *xunit;
          int myunit;
          char num[10];
          device_t dev;
          void *dev_private;
          const struct cfiattrdata *ia;
          device_lock_t dvl;
  
          cd = config_cfdriver_lookup(cf->cf_name);
          if (cd == NULL)
                  return NULL;
  
          ca = config_cfattach_lookup_cd(cd, cf->cf_atname);
          if (ca == NULL)
                  return NULL;
  
          /* get memory for all device vars */
          KASSERT(ca->ca_flags & DVF_PRIV_ALLOC);
          if (ca->ca_devsize > 0) {
                  dev_private = kmem_zalloc(ca->ca_devsize, KM_SLEEP);
          } else {
                  dev_private = NULL;
          }
          dev = kmem_zalloc(sizeof(*dev), KM_SLEEP);
  
          dev->dv_handle = args->devhandle;
  
          dev->dv_class = cd->cd_class;
          dev->dv_cfdata = cf;
          dev->dv_cfdriver = cd;
          dev->dv_cfattach = ca;
          dev->dv_activity_count = 0;
          dev->dv_activity_handlers = NULL;
          dev->dv_private = dev_private;
          dev->dv_flags = ca->ca_flags;   /* inherit flags from class */
          dev->dv_attaching = curlwp;
  
          myunit = config_unit_alloc(dev, cd, cf);
          if (myunit == -1) {
                  config_devfree(dev);
                  return NULL;
          }
  
          /* compute length of name and decimal expansion of unit number */
          lname = strlen(cd->cd_name);
          xunit = number(&num[sizeof(num)], myunit);
          lunit = &num[sizeof(num)] - xunit;
          if (lname + lunit > sizeof(dev->dv_xname))
                  panic("config_devalloc: device name too long");
  
          dvl = device_getlock(dev);
  
          mutex_init(&dvl->dvl_mtx, MUTEX_DEFAULT, IPL_NONE);
          cv_init(&dvl->dvl_cv, "pmfsusp");
  
          memcpy(dev->dv_xname, cd->cd_name, lname);
          memcpy(dev->dv_xname + lname, xunit, lunit);
          dev->dv_parent = parent;
          if (parent != NULL)
                  dev->dv_depth = parent->dv_depth + 1;
          else
                  dev->dv_depth = 0;
          dev->dv_flags |= DVF_ACTIVE;    /* always initially active */
          if (args->locators) {
                  KASSERT(parent); /* no locators at root */
                  ia = cfiattr_lookup(cfdata_ifattr(cf), parent->dv_cfdriver);
                  dev->dv_locators =
                      kmem_alloc(sizeof(int) * (ia->ci_loclen + 1), KM_SLEEP);
                  *dev->dv_locators++ = sizeof(int) * (ia->ci_loclen + 1);
                  memcpy(dev->dv_locators, args->locators,
                      sizeof(int) * ia->ci_loclen);
          }
          dev->dv_properties = prop_dictionary_create();
          KASSERT(dev->dv_properties != NULL);
  
          prop_dictionary_set_string_nocopy(dev->dv_properties,
              "device-driver", dev->dv_cfdriver->cd_name);
          prop_dictionary_set_uint16(dev->dv_properties,
              "device-unit", dev->dv_unit);
          if (parent != NULL) {
                  prop_dictionary_set_string(dev->dv_properties,
                      "device-parent", device_xname(parent));
          }
  
          dev->dv_localcount = kmem_zalloc(sizeof(*dev->dv_localcount),
              KM_SLEEP);
          localcount_init(dev->dv_localcount);
  
          if (dev->dv_cfdriver->cd_attrs != NULL)
                  config_add_attrib_dict(dev);
  
          return dev;
  }
  
  /*
   * Create an array of device attach attributes and add it
   * to the device's dv_properties dictionary.
   *
   * <key>interface-attributes</key>
   * <array>
   *    <dict>
   *       <key>attribute-name</key>
   *       <string>foo</string>
   *       <key>locators</key>
   *       <array>
   *          <dict>
   *             <key>loc-name</key>
   *             <string>foo-loc1</string>
   *          </dict>
   *          <dict>
   *             <key>loc-name</key>
   *             <string>foo-loc2</string>
   *             <key>default</key>
   *             <string>foo-loc2-default</string>
   *          </dict>
   *          ...
   *       </array>
   *    </dict>
   *    ...
   * </array>
   */
  
  static void
  config_add_attrib_dict(device_t dev)
  {
          int i, j;
          const struct cfiattrdata *ci;
          prop_dictionary_t attr_dict, loc_dict;
          prop_array_t attr_array, loc_array;
  
          if ((attr_array = prop_array_create()) == NULL)
                  return;
  
          for (i = 0; ; i++) {
                  if ((ci = dev->dv_cfdriver->cd_attrs[i]) == NULL)
                          break;
                  if ((attr_dict = prop_dictionary_create()) == NULL)
                          break;
                  prop_dictionary_set_string_nocopy(attr_dict, "attribute-name",
                      ci->ci_name);
  
                  /* Create an array of the locator names and defaults */
  
                  if (ci->ci_loclen != 0 &&
                      (loc_array = prop_array_create()) != NULL) {
                          for (j = 0; j < ci->ci_loclen; j++) {
                                  loc_dict = prop_dictionary_create();
                                  if (loc_dict == NULL)
                                          continue;
                                  prop_dictionary_set_string_nocopy(loc_dict,
                                      "loc-name", ci->ci_locdesc[j].cld_name);
                                  if (ci->ci_locdesc[j].cld_defaultstr != NULL)
                                          prop_dictionary_set_string_nocopy(
                                              loc_dict, "default",
                                              ci->ci_locdesc[j].cld_defaultstr);
                                  prop_array_set(loc_array, j, loc_dict);
                                  prop_object_release(loc_dict);
                          }
                          prop_dictionary_set_and_rel(attr_dict, "locators",
                              loc_array);
                  }
                  prop_array_add(attr_array, attr_dict);
                  prop_object_release(attr_dict);
          }
          if (i == 0)
                  prop_object_release(attr_array);
          else
                  prop_dictionary_set_and_rel(dev->dv_properties,
                      "interface-attributes", attr_array);
  
          return;
  }
  
  /*
   * Attach a found device.
   */
  static device_t
  config_attach_internal(device_t parent, cfdata_t cf, void *aux, cfprint_t print,
      const struct cfargs_internal * const args)
  {
          device_t dev;
          struct cftable *ct;
          const char *drvname;
          bool deferred;
  
          KASSERT(KERNEL_LOCKED_P());
  
          dev = config_devalloc(parent, cf, args);
          if (!dev)
                  panic("config_attach: allocation of device softc failed");
  
          /* XXX redundant - see below? */
          if (cf->cf_fstate != FSTATE_STAR) {
                  KASSERT(cf->cf_fstate == FSTATE_NOTFOUND);
                  cf->cf_fstate = FSTATE_FOUND;
          }
  
          config_devlink(dev);
  
          if (config_do_twiddle && cold)
                  twiddle();
          else
                  aprint_naive("Found ");
          /*
           * We want the next two printfs for normal, verbose, and quiet,
           * but not silent (in which case, we're twiddling, instead).
           */
          if (parent == ROOT) {
                  aprint_naive("%s (root)", device_xname(dev));
                  aprint_normal("%s (root)", device_xname(dev));
          } else {
                  aprint_naive("%s at %s", device_xname(dev),
                      device_xname(parent));
                  aprint_normal("%s at %s", device_xname(dev),
                      device_xname(parent));
                  if (print)
                          (void) (*print)(aux, NULL);
          }
  
          /*
           * Before attaching, clobber any unfound devices that are
           * otherwise identical.
           * XXX code above is redundant?
           */
          drvname = dev->dv_cfdriver->cd_name;
          TAILQ_FOREACH(ct, &allcftables, ct_list) {
                  for (cf = ct->ct_cfdata; cf->cf_name; cf++) {
                          if (STREQ(cf->cf_name, drvname) &&
                              cf->cf_unit == dev->dv_unit) {
                                  if (cf->cf_fstate == FSTATE_NOTFOUND)
                                          cf->cf_fstate = FSTATE_FOUND;
                          }
                  }
          }
          device_register(dev, aux);
  
          /* Let userland know */
          devmon_report_device(dev, true);
  
          /*
           * Prevent detach until the driver's attach function, and all
           * deferred actions, have finished.
           */
          config_pending_incr(dev);
  
          /* Call the driver's attach function.  */
          (*dev->dv_cfattach->ca_attach)(parent, dev, aux);
  
          /*
           * Allow other threads to acquire references to the device now
           * that the driver's attach function is done.
           */
          mutex_enter(&config_misc_lock);
          KASSERT(dev->dv_attaching == curlwp);
          dev->dv_attaching = NULL;
          cv_broadcast(&config_misc_cv);
          mutex_exit(&config_misc_lock);
  
          /*
           * Synchronous parts of attach are done.  Allow detach, unless
           * the driver's attach function scheduled deferred actions.
           */
          config_pending_decr(dev);
  
          mutex_enter(&config_misc_lock);
          deferred = (dev->dv_pending != 0);
          mutex_exit(&config_misc_lock);
  
          if (!deferred && !device_pmf_is_registered(dev))
                  aprint_debug_dev(dev,
                      "WARNING: power management not supported\n");
  
          config_process_deferred(&deferred_config_queue, dev);
  
          device_register_post_config(dev, aux);
          rnd_add_uint32(&rnd_autoconf_source, 0);
          return dev;
  }
  
  device_t
  config_attach(device_t parent, cfdata_t cf, void *aux, cfprint_t print,
      const struct cfargs *cfargs)
  {
          struct cfargs_internal store;
  
          KASSERT(KERNEL_LOCKED_P());
  
          return config_attach_internal(parent, cf, aux, print,
              cfargs_canonicalize(cfargs, &store));
  }
  
  /*
   * As above, but for pseudo-devices.  Pseudo-devices attached in this
   * way are silently inserted into the device tree, and their children
   * attached.
   *
   * Note that because pseudo-devices are attached silently, any information
   * the attach routine wishes to print should be prefixed with the device
   * name by the attach routine.
   */
  device_t
  config_attach_pseudo(cfdata_t cf)
  {
          device_t dev;
  
          KERNEL_LOCK(1, NULL);
  
          struct cfargs_internal args = { };
          dev = config_devalloc(ROOT, cf, &args);
          if (!dev)
                  goto out;
  
          /* XXX mark busy in cfdata */
  
          if (cf->cf_fstate != FSTATE_STAR) {
                  KASSERT(cf->cf_fstate == FSTATE_NOTFOUND);
                  cf->cf_fstate = FSTATE_FOUND;
          }
  
          config_devlink(dev);
  
  #if 0   /* XXXJRT not yet */
          device_register(dev, NULL);     /* like a root node */
  #endif
  
          /* Let userland know */
          devmon_report_device(dev, true);
  
          /*
           * Prevent detach until the driver's attach function, and all
           * deferred actions, have finished.
           */
          config_pending_incr(dev);
  
          /* Call the driver's attach function.  */
          (*dev->dv_cfattach->ca_attach)(ROOT, dev, NULL);
  
          /*
           * Allow other threads to acquire references to the device now
           * that the driver's attach function is done.
           */
          mutex_enter(&config_misc_lock);
          KASSERT(dev->dv_attaching == curlwp);
          dev->dv_attaching = NULL;
          cv_broadcast(&config_misc_cv);
          mutex_exit(&config_misc_lock);
  
          /*
           * Synchronous parts of attach are done.  Allow detach, unless
           * the driver's attach function scheduled deferred actions.
           */
          config_pending_decr(dev);
  
          config_process_deferred(&deferred_config_queue, dev);
  
  out:    KERNEL_UNLOCK_ONE(NULL);
          return dev;
  }
  
  /*
   * Caller must hold alldevs_lock.
   */
  static void
  config_collect_garbage(struct devicelist *garbage)
  {
          device_t dv;
  
          KASSERT(!cpu_intr_p());
          KASSERT(!cpu_softintr_p());
          KASSERT(mutex_owned(&alldevs_lock));
  
          while (alldevs_nwrite == 0 && alldevs_nread == 0 && alldevs_garbage) {
                  TAILQ_FOREACH(dv, &alldevs, dv_list) {
                          if (dv->dv_del_gen != 0)
                                  break;
                  }
                  if (dv == NULL) {
                          alldevs_garbage = false;
                          break;
                  }
                  config_devunlink(dv, garbage);
          }
          KASSERT(mutex_owned(&alldevs_lock));
  }
  
  static void
  config_dump_garbage(struct devicelist *garbage)
  {
          device_t dv;
  
          while ((dv = TAILQ_FIRST(garbage)) != NULL) {
                  TAILQ_REMOVE(garbage, dv, dv_list);
                  config_devdelete(dv);
          }
  }
  
  static int
  config_detach_enter(device_t dev)
  {
          struct lwp *l __diagused;
          int error = 0;
  
          mutex_enter(&config_misc_lock);
  
          /*
           * Wait until attach has fully completed, and until any
           * concurrent detach (e.g., drvctl racing with USB event
           * thread) has completed.
           *
           * Caller must hold alldevs_nread or alldevs_nwrite (e.g., via
           * deviter) to ensure the winner of the race doesn't free the
           * device leading the loser of the race into use-after-free.
           *
           * XXX Not all callers do this!
           */
          while (dev->dv_pending || dev->dv_detaching) {
                  KASSERTMSG(dev->dv_detaching != curlwp,
                      "recursively detaching %s", device_xname(dev));
                  error = cv_wait_sig(&config_misc_cv, &config_misc_lock);
                  if (error)
                          goto out;
          }
  
          /*
           * Attach has completed, and no other concurrent detach is
           * running.  Claim the device for detaching.  This will cause
           * all new attempts to acquire references to block.
           */
          KASSERTMSG((l = dev->dv_attaching) == NULL,
              "lwp %ld [%s] @ %p attaching %s",
              (long)l->l_lid, (l->l_name ? l->l_name : l->l_proc->p_comm), l,
              device_xname(dev));
          KASSERTMSG((l = dev->dv_detaching) == NULL,
              "lwp %ld [%s] @ %p detaching %s",
              (long)l->l_lid, (l->l_name ? l->l_name : l->l_proc->p_comm), l,
              device_xname(dev));
          dev->dv_detaching = curlwp;
  
  out:    mutex_exit(&config_misc_lock);
          return error;
  }
  
  static void
  config_detach_exit(device_t dev)
  {
          struct lwp *l __diagused;
  
          mutex_enter(&config_misc_lock);
          KASSERTMSG(dev->dv_detaching != NULL, "not detaching %s",
              device_xname(dev));
          KASSERTMSG((l = dev->dv_detaching) == curlwp,
              "lwp %ld [%s] @ %p detaching %s",
              (long)l->l_lid, (l->l_name ? l->l_name : l->l_proc->p_comm), l,
              device_xname(dev));
          dev->dv_detaching = NULL;
          cv_broadcast(&config_misc_cv);
          mutex_exit(&config_misc_lock);
  }
  
  /*
   * Detach a device.  Optionally forced (e.g. because of hardware
   * removal) and quiet.  Returns zero if successful, non-zero
   * (an error code) otherwise.
   *
   * Note that this code wants to be run from a process context, so
   * that the detach can sleep to allow processes which have a device
   * open to run and unwind their stacks.
   */
  int
  config_detach(device_t dev, int flags)
  {
          struct alldevs_foray af;
          struct cftable *ct;
          cfdata_t cf;
          const struct cfattach *ca;
          struct cfdriver *cd;
          device_t d __diagused;
          int rv = 0;
  
          KERNEL_LOCK(1, NULL);
  
          cf = dev->dv_cfdata;
          KASSERTMSG((cf == NULL || cf->cf_fstate == FSTATE_FOUND ||
                  cf->cf_fstate == FSTATE_STAR),
              "config_detach: %s: bad device fstate: %d",
              device_xname(dev), cf ? cf->cf_fstate : -1);
  
          cd = dev->dv_cfdriver;
          KASSERT(cd != NULL);
  
          ca = dev->dv_cfattach;
          KASSERT(ca != NULL);
  
          /*
           * Only one detach at a time, please -- and not until fully
           * attached.
           */
          rv = config_detach_enter(dev);
          if (rv) {
                  KERNEL_UNLOCK_ONE(NULL);
                  return rv;
          }
  
          mutex_enter(&alldevs_lock);
          if (dev->dv_del_gen != 0) {
                  mutex_exit(&alldevs_lock);
  #ifdef DIAGNOSTIC
                  printf("%s: %s is already detached\n", __func__,
                      device_xname(dev));
  #endif /* DIAGNOSTIC */
                  config_detach_exit(dev);
                  KERNEL_UNLOCK_ONE(NULL);
                  return ENOENT;
          }
          alldevs_nwrite++;
          mutex_exit(&alldevs_lock);
  
          /*
           * Call the driver's .ca_detach function, unless it has none or
           * we are skipping it because it's unforced shutdown time and
           * the driver didn't ask to detach on shutdown.
           */
          if (!detachall &&
              (flags & (DETACH_SHUTDOWN|DETACH_FORCE)) == DETACH_SHUTDOWN &&
              (dev->dv_flags & DVF_DETACH_SHUTDOWN) == 0) {
                  rv = EOPNOTSUPP;
          } else if (ca->ca_detach != NULL) {
                  rv = (*ca->ca_detach)(dev, flags);
          } else
                  rv = EOPNOTSUPP;
  
          KASSERTMSG(!dev->dv_detach_done, "%s detached twice, error=%d",
              device_xname(dev), rv);
  
          /*
           * If it was not possible to detach the device, then we either
           * panic() (for the forced but failed case), or return an error.
           */
          if (rv) {
                  /*
                   * Detach failed -- likely EOPNOTSUPP or EBUSY.  Driver
                   * must not have called config_detach_commit.
                   */
                  KASSERTMSG(!dev->dv_detach_committed,
                      "%s committed to detaching and then backed out, error=%d",
                      device_xname(dev), rv);
                  if (flags & DETACH_FORCE) {
                          panic("config_detach: forced detach of %s failed (%d)",
                              device_xname(dev), rv);
                  }
                  goto out;
          }
  
          /*
           * The device has now been successfully detached.
           */
          dev->dv_detach_done = true;
  
          /*
           * If .ca_detach didn't commit to detach, then do that for it.
           * This wakes any pending device_lookup_acquire calls so they
           * will fail.
           */
          config_detach_commit(dev);
  
          /*
           * If it was possible to detach the device, ensure that the
           * device is deactivated.
           */
          dev->dv_flags &= ~DVF_ACTIVE; /* XXXSMP */
  
          /*
           * Wait for all device_lookup_acquire references -- mostly, for
           * all attempts to open the device -- to drain.  It is the
           * responsibility of .ca_detach to ensure anything with open
           * references will be interrupted and release them promptly,
           * not block indefinitely.  All new attempts to acquire
           * references will fail, as config_detach_commit has arranged
           * by now.
           */
          mutex_enter(&config_misc_lock);
          localcount_drain(dev->dv_localcount,
              &config_misc_cv, &config_misc_lock);
          mutex_exit(&config_misc_lock);
  
          /* Let userland know */
          devmon_report_device(dev, false);
  
  #ifdef DIAGNOSTIC
          /*
           * Sanity: If you're successfully detached, you should have no
           * children.  (Note that because children must be attached
           * after parents, we only need to search the latter part of
           * the list.)
           */
          mutex_enter(&alldevs_lock);
          for (d = TAILQ_NEXT(dev, dv_list); d != NULL;
              d = TAILQ_NEXT(d, dv_list)) {
                  if (d->dv_parent == dev && d->dv_del_gen == 0) {
                          printf("config_detach: detached device %s"
                              " has children %s\n", device_xname(dev),
                              device_xname(d));
                          panic("config_detach");
                  }
          }
          mutex_exit(&alldevs_lock);
  #endif
  
          /* notify the parent that the child is gone */
          if (dev->dv_parent) {
                  device_t p = dev->dv_parent;
                  if (p->dv_cfattach->ca_childdetached)
                          (*p->dv_cfattach->ca_childdetached)(p, dev);
          }
  
          /*
           * Mark cfdata to show that the unit can be reused, if possible.
           */
          TAILQ_FOREACH(ct, &allcftables, ct_list) {
                  for (cf = ct->ct_cfdata; cf->cf_name; cf++) {
                          if (STREQ(cf->cf_name, cd->cd_name)) {
                                  if (cf->cf_fstate == FSTATE_FOUND &&
                                      cf->cf_unit == dev->dv_unit)
                                          cf->cf_fstate = FSTATE_NOTFOUND;
                          }
                  }
          }
  
          if (dev->dv_cfdata != NULL && (flags & DETACH_QUIET) == 0)
                  aprint_normal_dev(dev, "detached\n");
  
  out:
          config_detach_exit(dev);
  
          config_alldevs_enter(&af);
          KASSERT(alldevs_nwrite != 0);
          --alldevs_nwrite;
          if (rv == 0 && dev->dv_del_gen == 0) {
                  if (alldevs_nwrite == 0 && alldevs_nread == 0)
                          config_devunlink(dev, &af.af_garbage);
                  else {
                          dev->dv_del_gen = alldevs_gen;
                          alldevs_garbage = true;
                  }
          }
          config_alldevs_exit(&af);
  
          KERNEL_UNLOCK_ONE(NULL);
  
          return rv;
  }
  
  /*
   * config_detach_commit(dev)
   *
   *      Issued by a driver's .ca_detach routine to notify anyone
   *      waiting in device_lookup_acquire that the driver is committed
   *      to detaching the device, which allows device_lookup_acquire to
   *      wake up and fail immediately.
   *
   *      Safe to call multiple times -- idempotent.  Must be called
   *      during config_detach_enter/exit.  Safe to use with
   *      device_lookup because the device is not actually removed from
   *      the table until after config_detach_exit.
   */
  void
  config_detach_commit(device_t dev)
  {
          struct lwp *l __diagused;
  
          mutex_enter(&config_misc_lock);
          KASSERTMSG(dev->dv_detaching != NULL, "not detaching %s",
              device_xname(dev));
          KASSERTMSG((l = dev->dv_detaching) == curlwp,
              "lwp %ld [%s] @ %p detaching %s",
              (long)l->l_lid, (l->l_name ? l->l_name : l->l_proc->p_comm), l,
              device_xname(dev));
          dev->dv_detach_committed = true;
          cv_broadcast(&config_misc_cv);
          mutex_exit(&config_misc_lock);
  }
  
  int
  config_detach_children(device_t parent, int flags)
  {
          device_t dv;
          deviter_t di;
          int error = 0;
  
          KASSERT(KERNEL_LOCKED_P());
  
          for (dv = deviter_first(&di, DEVITER_F_RW); dv != NULL;
               dv = deviter_next(&di)) {
                  if (device_parent(dv) != parent)
                          continue;
                  if ((error = config_detach(dv, flags)) != 0)
                          break;
          }
          deviter_release(&di);
          return error;
  }
  
  device_t
  shutdown_first(struct shutdown_state *s)
  {
          if (!s->initialized) {
                  deviter_init(&s->di, DEVITER_F_SHUTDOWN|DEVITER_F_LEAVES_FIRST);
                  s->initialized = true;
          }
          return shutdown_next(s);
  }
  
  device_t
  shutdown_next(struct shutdown_state *s)
  {
          device_t dv;
  
          while ((dv = deviter_next(&s->di)) != NULL && !device_is_active(dv))
                  ;
  
          if (dv == NULL)
                  s->initialized = false;
  
          return dv;
  }
  
  bool
  config_detach_all(int how)
  {
          static struct shutdown_state s;
          device_t curdev;
          bool progress = false;
          int flags;
  
          KERNEL_LOCK(1, NULL);
  
          if ((how & (RB_NOSYNC|RB_DUMP)) != 0)
                  goto out;
  
          if ((how & RB_POWERDOWN) == RB_POWERDOWN)
                  flags = DETACH_SHUTDOWN | DETACH_POWEROFF;
          else
                  flags = DETACH_SHUTDOWN;
  
          for (curdev = shutdown_first(&s); curdev != NULL;
               curdev = shutdown_next(&s)) {
                  aprint_debug(" detaching %s, ", device_xname(curdev));
                  if (config_detach(curdev, flags) == 0) {
                          progress = true;
                          aprint_debug("success.");
                  } else
                          aprint_debug("failed.");
          }
  
  out:    KERNEL_UNLOCK_ONE(NULL);
          return progress;
  }
  
  static bool
  device_is_ancestor_of(device_t ancestor, device_t descendant)
  {
          device_t dv;
  
          for (dv = descendant; dv != NULL; dv = device_parent(dv)) {
                  if (device_parent(dv) == ancestor)
                          return true;
          }
          return false;
  }
  
  int
  config_deactivate(device_t dev)
  {
          deviter_t di;
          const struct cfattach *ca;
          device_t descendant;
          int s, rv = 0, oflags;
  
          for (descendant = deviter_first(&di, DEVITER_F_ROOT_FIRST);
               descendant != NULL;
               descendant = deviter_next(&di)) {
                  if (dev != descendant &&
                      !device_is_ancestor_of(dev, descendant))
                          continue;
  
                  if ((descendant->dv_flags & DVF_ACTIVE) == 0)
                          continue;
  
                  ca = descendant->dv_cfattach;
                  oflags = descendant->dv_flags;
  
                  descendant->dv_flags &= ~DVF_ACTIVE;
                  if (ca->ca_activate == NULL)
                          continue;
                  s = splhigh();
                  rv = (*ca->ca_activate)(descendant, DVACT_DEACTIVATE);
                  splx(s);
                  if (rv != 0)
                          descendant->dv_flags = oflags;
          }
          deviter_release(&di);
          return rv;
  }
  
  /*
   * Defer the configuration of the specified device until all
   * of its parent's devices have been attached.
   */
  void
  config_defer(device_t dev, void (*func)(device_t))
  {
          struct deferred_config *dc;
  
          if (dev->dv_parent == NULL)
                  panic("config_defer: can't defer config of a root device");
  
          dc = kmem_alloc(sizeof(*dc), KM_SLEEP);
  
          config_pending_incr(dev);
  
          mutex_enter(&config_misc_lock);
  #ifdef DIAGNOSTIC
          struct deferred_config *odc;
          TAILQ_FOREACH(odc, &deferred_config_queue, dc_queue) {
                  if (odc->dc_dev == dev)
                          panic("config_defer: deferred twice");
          }
  #endif
          dc->dc_dev = dev;
          dc->dc_func = func;
          TAILQ_INSERT_TAIL(&deferred_config_queue, dc, dc_queue);
          mutex_exit(&config_misc_lock);
  }
  
  /*
   * Defer some autoconfiguration for a device until after interrupts
   * are enabled.
   */
  void
  config_interrupts(device_t dev, void (*func)(device_t))
  {
          struct deferred_config *dc;
  
          /*
           * If interrupts are enabled, callback now.
           */
          if (cold == 0) {
                  (*func)(dev);
                  return;
          }
  
          dc = kmem_alloc(sizeof(*dc), KM_SLEEP);
  
          config_pending_incr(dev);
  
          mutex_enter(&config_misc_lock);
  #ifdef DIAGNOSTIC
          struct deferred_config *odc;
          TAILQ_FOREACH(odc, &interrupt_config_queue, dc_queue) {
                  if (odc->dc_dev == dev)
                          panic("config_interrupts: deferred twice");
          }
  #endif
          dc->dc_dev = dev;
          dc->dc_func = func;
          TAILQ_INSERT_TAIL(&interrupt_config_queue, dc, dc_queue);
          mutex_exit(&config_misc_lock);
  }
  
  /*
   * Defer some autoconfiguration for a device until after root file system
   * is mounted (to load firmware etc).
   */
  void
  config_mountroot(device_t dev, void (*func)(device_t))
  {
          struct deferred_config *dc;
  
          /*
           * If root file system is mounted, callback now.
           */
          if (root_is_mounted) {
                  (*func)(dev);
                  return;
          }
  
          dc = kmem_alloc(sizeof(*dc), KM_SLEEP);
  
          mutex_enter(&config_misc_lock);
  #ifdef DIAGNOSTIC
          struct deferred_config *odc;
          TAILQ_FOREACH(odc, &mountroot_config_queue, dc_queue) {
                  if (odc->dc_dev == dev)
                          panic("%s: deferred twice", __func__);
          }
  #endif
  
          dc->dc_dev = dev;
          dc->dc_func = func;
          TAILQ_INSERT_TAIL(&mountroot_config_queue, dc, dc_queue);
          mutex_exit(&config_misc_lock);
  }
  
  /*
   * Process a deferred configuration queue.
   */
  static void
  config_process_deferred(struct deferred_config_head *queue, device_t parent)
  {
          struct deferred_config *dc;
  
          KASSERT(KERNEL_LOCKED_P());
  
          mutex_enter(&config_misc_lock);
          dc = TAILQ_FIRST(queue);
          while (dc) {
                  if (parent == NULL || dc->dc_dev->dv_parent == parent) {
                          TAILQ_REMOVE(queue, dc, dc_queue);
                          mutex_exit(&config_misc_lock);
  
                          (*dc->dc_func)(dc->dc_dev);
                          config_pending_decr(dc->dc_dev);
                          kmem_free(dc, sizeof(*dc));
  
                          mutex_enter(&config_misc_lock);
                          /* Restart, queue might have changed */
                          dc = TAILQ_FIRST(queue);
                  } else {
                          dc = TAILQ_NEXT(dc, dc_queue);
                  }
          }
          mutex_exit(&config_misc_lock);
  }
  
  /*
   * Manipulate the config_pending semaphore.
   */
  void
  config_pending_incr(device_t dev)
  {
  
          mutex_enter(&config_misc_lock);
          KASSERTMSG(dev->dv_pending < INT_MAX,
              "%s: excess config_pending_incr", device_xname(dev));
          if (dev->dv_pending++ == 0)
                  TAILQ_INSERT_TAIL(&config_pending, dev, dv_pending_list);
  #ifdef DEBUG_AUTOCONF
          printf("%s: %s %d\n", __func__, device_xname(dev), dev->dv_pending);
  #endif
          mutex_exit(&config_misc_lock);
  }
  
  void
  config_pending_decr(device_t dev)
  {
  
          mutex_enter(&config_misc_lock);
          KASSERTMSG(dev->dv_pending > 0,
              "%s: excess config_pending_decr", device_xname(dev));
          if (--dev->dv_pending == 0) {
                  TAILQ_REMOVE(&config_pending, dev, dv_pending_list);
                  cv_broadcast(&config_misc_cv);
          }
  #ifdef DEBUG_AUTOCONF
          printf("%s: %s %d\n", __func__, device_xname(dev), dev->dv_pending);
  #endif
          mutex_exit(&config_misc_lock);
  }
  
  /*
   * Register a "finalization" routine.  Finalization routines are
   * called iteratively once all real devices have been found during
   * autoconfiguration, for as long as any one finalizer has done
   * any work.
   */
  int
  config_finalize_register(device_t dev, int (*fn)(device_t))
  {
          struct finalize_hook *f;
          int error = 0;
  
          KERNEL_LOCK(1, NULL);
  
          /*
           * If finalization has already been done, invoke the
           * callback function now.
           */
          if (config_finalize_done) {
                  while ((*fn)(dev) != 0)
                          /* loop */ ;
                  goto out;
          }
  
          /* Ensure this isn't already on the list. */
          TAILQ_FOREACH(f, &config_finalize_list, f_list) {
                  if (f->f_func == fn && f->f_dev == dev) {
                          error = EEXIST;
                          goto out;
                  }
          }
  
          f = kmem_alloc(sizeof(*f), KM_SLEEP);
          f->f_func = fn;
          f->f_dev = dev;
          TAILQ_INSERT_TAIL(&config_finalize_list, f, f_list);
  
          /* Success!  */
          error = 0;
  
  out:    KERNEL_UNLOCK_ONE(NULL);
          return error;
  }
  
  void
  config_finalize(void)
  {
          struct finalize_hook *f;
          struct pdevinit *pdev;
          extern struct pdevinit pdevinit[];
          int errcnt, rv;
  
          /*
           * Now that device driver threads have been created, wait for
           * them to finish any deferred autoconfiguration.
           */
          mutex_enter(&config_misc_lock);
          while (!TAILQ_EMPTY(&config_pending)) {
                  device_t dev;
                  int error;
  
                  error = cv_timedwait(&config_misc_cv, &config_misc_lock,
                      mstohz(1000));
                  if (error == EWOULDBLOCK) {
                          aprint_debug("waiting for devices:");
                          TAILQ_FOREACH(dev, &config_pending, dv_pending_list)
                                  aprint_debug(" %s", device_xname(dev));
                          aprint_debug("\n");
                  }
          }
          mutex_exit(&config_misc_lock);
  
          KERNEL_LOCK(1, NULL);
  
          /* Attach pseudo-devices. */
          for (pdev = pdevinit; pdev->pdev_attach != NULL; pdev++)
                  (*pdev->pdev_attach)(pdev->pdev_count);
  
          /* Run the hooks until none of them does any work. */
          do {
                  rv = 0;
                  TAILQ_FOREACH(f, &config_finalize_list, f_list)
                          rv |= (*f->f_func)(f->f_dev);
          } while (rv != 0);
  
          config_finalize_done = 1;
  
          /* Now free all the hooks. */
          while ((f = TAILQ_FIRST(&config_finalize_list)) != NULL) {
                  TAILQ_REMOVE(&config_finalize_list, f, f_list);
                  kmem_free(f, sizeof(*f));
          }
  
          KERNEL_UNLOCK_ONE(NULL);
  
          errcnt = aprint_get_error_count();
          if ((boothowto & (AB_QUIET|AB_SILENT)) != 0 &&
              (boothowto & AB_VERBOSE) == 0) {
                  mutex_enter(&config_misc_lock);
                  if (config_do_twiddle) {
                          config_do_twiddle = 0;
                          printf_nolog(" done.\n");
                  }
                  mutex_exit(&config_misc_lock);
          }
          if (errcnt != 0) {
                  printf("WARNING: %d error%s while detecting hardware; "
                      "check system log.\n", errcnt,
                      errcnt == 1 ? "" : "s");
          }
  }
  
  void
  config_twiddle_init(void)
  {
  
          if ((boothowto & (AB_SILENT|AB_VERBOSE)) == AB_SILENT) {
                  config_do_twiddle = 1;
          }
          callout_setfunc(&config_twiddle_ch, config_twiddle_fn, NULL);
  }
  
  void
  config_twiddle_fn(void *cookie)
  {
  
          mutex_enter(&config_misc_lock);
          if (config_do_twiddle) {
                  twiddle();
                  callout_schedule(&config_twiddle_ch, mstohz(100));
          }
          mutex_exit(&config_misc_lock);
  }
  
  static void
  config_alldevs_enter(struct alldevs_foray *af)
  {
          TAILQ_INIT(&af->af_garbage);
          mutex_enter(&alldevs_lock);
          config_collect_garbage(&af->af_garbage);
  }
  
  static void
  config_alldevs_exit(struct alldevs_foray *af)
  {
          mutex_exit(&alldevs_lock);
          config_dump_garbage(&af->af_garbage);
  }
  
  /*
   * device_lookup:
   *
   *      Look up a device instance for a given driver.
   *
   *      Caller is responsible for ensuring the device's state is
   *      stable, either by holding a reference already obtained with
   *      device_lookup_acquire or by otherwise ensuring the device is
   *      attached and can't be detached (e.g., holding an open device
   *      node and ensuring *_detach calls vdevgone).
   *
   *      XXX Find a way to assert this.
   *
   *      Safe for use up to and including interrupt context at IPL_VM.
   *      Never sleeps.
   */
  device_t
  device_lookup(cfdriver_t cd, int unit)
  {
          device_t dv;
  
          mutex_enter(&alldevs_lock);
          if (unit < 0 || unit >= cd->cd_ndevs)
                  dv = NULL;
          else if ((dv = cd->cd_devs[unit]) != NULL && dv->dv_del_gen != 0)
                  dv = NULL;
          mutex_exit(&alldevs_lock);
  
          return dv;
  }
  
  /*
   * device_lookup_private:
   *
   *      Look up a softc instance for a given driver.
   */
  void *
  device_lookup_private(cfdriver_t cd, int unit)
  {
  
          return device_private(device_lookup(cd, unit));
  }
  
  /*
   * device_lookup_acquire:
   *
   *      Look up a device instance for a given driver, and return a
   *      reference to it that must be released by device_release.
   *
   *      => If the device is still attaching, blocks until *_attach has
   *         returned.
   *
   *      => If the device is detaching, blocks until *_detach has
   *         returned.  May succeed or fail in that case, depending on
   *         whether *_detach has backed out (EBUSY) or committed to
   *         detaching.
   *
   *      May sleep.
   */
  device_t
  device_lookup_acquire(cfdriver_t cd, int unit)
  {
          device_t dv;
  
          ASSERT_SLEEPABLE();
  
          /* XXX This should have a pserialized fast path -- TBD.  */
          mutex_enter(&config_misc_lock);
          mutex_enter(&alldevs_lock);
  retry:  if (unit < 0 || unit >= cd->cd_ndevs ||
              (dv = cd->cd_devs[unit]) == NULL ||
              dv->dv_del_gen != 0 ||
              dv->dv_detach_committed) {
                  dv = NULL;
          } else {
                  /*
                   * Wait for the device to stabilize, if attaching or
                   * detaching.  Either way we must wait for *_attach or
                   * *_detach to complete, and either way we must retry:
                   * even if detaching, *_detach might fail (EBUSY) so
                   * the device may still be there.
                   */
                  if ((dv->dv_attaching != NULL && dv->dv_attaching != curlwp) ||
                      dv->dv_detaching != NULL) {
                          mutex_exit(&alldevs_lock);
                          cv_wait(&config_misc_cv, &config_misc_lock);
                          mutex_enter(&alldevs_lock);
                          goto retry;
                  }
                  localcount_acquire(dv->dv_localcount);
          }
          mutex_exit(&alldevs_lock);
          mutex_exit(&config_misc_lock);
  
          return dv;
  }
  
  /*
   * device_release:
   *
   *      Release a reference to a device acquired with
   *      device_lookup_acquire.
   */
  void
  device_release(device_t dv)
  {
  
          localcount_release(dv->dv_localcount,
              &config_misc_cv, &config_misc_lock);
  }
  
  /*
   * device_find_by_xname:
   *
   *      Returns the device of the given name or NULL if it doesn't exist.
   */
  device_t
  device_find_by_xname(const char *name)
  {
          device_t dv;
          deviter_t di;
  
          for (dv = deviter_first(&di, 0); dv != NULL; dv = deviter_next(&di)) {
                  if (strcmp(device_xname(dv), name) == 0)
                          break;
          }
          deviter_release(&di);
  
          return dv;
  }
  
  /*
   * device_find_by_driver_unit:
   *
   *      Returns the device of the given driver name and unit or
   *      NULL if it doesn't exist.
   */
  device_t
  device_find_by_driver_unit(const char *name, int unit)
  {
          struct cfdriver *cd;
  
          if ((cd = config_cfdriver_lookup(name)) == NULL)
                  return NULL;
          return device_lookup(cd, unit);
  }
  
  static bool
  match_strcmp(const char * const s1, const char * const s2)
  {
          return strcmp(s1, s2) == 0;
  }
  
  static bool
  match_pmatch(const char * const s1, const char * const s2)
  {
          return pmatch(s1, s2, NULL) == 2;
  }
  
  static bool
  strarray_match_internal(const char ** const strings,
      unsigned int const nstrings, const char * const str,
      unsigned int * const indexp,
      bool (*match_fn)(const char *, const char *))
  {
          unsigned int i;
  
          if (strings == NULL || nstrings == 0) {
                  return false;
          }
  
          for (i = 0; i < nstrings; i++) {
                  if ((*match_fn)(strings[i], str)) {
                          *indexp = i;
                          return true;
                  }
          }
  
          return false;
  }
  
  static int
  strarray_match(const char ** const strings, unsigned int const nstrings,
      const char * const str)
  {
          unsigned int idx;
  
          if (strarray_match_internal(strings, nstrings, str, &idx,
                                      match_strcmp)) {
                  return (int)(nstrings - idx);
          }
          return 0;
  }
  
  static int
  strarray_pmatch(const char ** const strings, unsigned int const nstrings,
      const char * const pattern)
  {
          unsigned int idx;
  
          if (strarray_match_internal(strings, nstrings, pattern, &idx,
                                      match_pmatch)) {
                  return (int)(nstrings - idx);
          }
          return 0;
  }
  
  static int
  device_compatible_match_strarray_internal(
      const char **device_compats, int ndevice_compats,
      const struct device_compatible_entry *driver_compats,
      const struct device_compatible_entry **matching_entryp,
      int (*match_fn)(const char **, unsigned int, const char *))
  {
          const struct device_compatible_entry *dce = NULL;
          int rv;
  
          if (ndevice_compats == 0 || device_compats == NULL ||
              driver_compats == NULL)
                  return 0;
  
          for (dce = driver_compats; dce->compat != NULL; dce++) {
                  rv = (*match_fn)(device_compats, ndevice_compats, dce->compat);
                  if (rv != 0) {
                          if (matching_entryp != NULL) {
                                  *matching_entryp = dce;
                          }
                          return rv;
                  }
          }
          return 0;
  }
  
  /*
   * device_compatible_match:
   *
   *      Match a driver's "compatible" data against a device's
   *      "compatible" strings.  Returns resulted weighted by
   *      which device "compatible" string was matched.
   */
  int
  device_compatible_match(const char **device_compats, int ndevice_compats,
      const struct device_compatible_entry *driver_compats)
  {
          return device_compatible_match_strarray_internal(device_compats,
              ndevice_compats, driver_compats, NULL, strarray_match);
  }
  
  /*
   * device_compatible_pmatch:
   *
   *      Like device_compatible_match(), but uses pmatch(9) to compare
   *      the device "compatible" strings against patterns in the
   *      driver's "compatible" data.
   */
  int
  device_compatible_pmatch(const char **device_compats, int ndevice_compats,
      const struct device_compatible_entry *driver_compats)
  {
          return device_compatible_match_strarray_internal(device_compats,
              ndevice_compats, driver_compats, NULL, strarray_pmatch);
  }
  
  static int
  device_compatible_match_strlist_internal(
      const char * const device_compats, size_t const device_compatsize,
      const struct device_compatible_entry *driver_compats,
      const struct device_compatible_entry **matching_entryp,
      int (*match_fn)(const char *, size_t, const char *))
  {
          const struct device_compatible_entry *dce = NULL;
          int rv;
  
          if (device_compats == NULL || device_compatsize == 0 ||
              driver_compats == NULL)
                  return 0;
  
          for (dce = driver_compats; dce->compat != NULL; dce++) {
                  rv = (*match_fn)(device_compats, device_compatsize,
                      dce->compat);
                  if (rv != 0) {
                          if (matching_entryp != NULL) {
                                  *matching_entryp = dce;
                          }
                          return rv;
                  }
          }
          return 0;
  }
  
  /*
   * device_compatible_match_strlist:
   *
   *      Like device_compatible_match(), but take the device
   *      "compatible" strings as an OpenFirmware-style string
   *      list.
   */
  int
  device_compatible_match_strlist(
      const char * const device_compats, size_t const device_compatsize,
      const struct device_compatible_entry *driver_compats)
  {
          return device_compatible_match_strlist_internal(device_compats,
              device_compatsize, driver_compats, NULL, strlist_match);
  }
  
  /*
   * device_compatible_pmatch_strlist:
   *
   *      Like device_compatible_pmatch(), but take the device
   *      "compatible" strings as an OpenFirmware-style string
   *      list.
   */
  int
  device_compatible_pmatch_strlist(
      const char * const device_compats, size_t const device_compatsize,
      const struct device_compatible_entry *driver_compats)
  {
          return device_compatible_match_strlist_internal(device_compats,
              device_compatsize, driver_compats, NULL, strlist_pmatch);
  }
  
  static int
  device_compatible_match_id_internal(
      uintptr_t const id, uintptr_t const mask, uintptr_t const sentinel_id,
      const struct device_compatible_entry *driver_compats,
      const struct device_compatible_entry **matching_entryp)
  {
          const struct device_compatible_entry *dce = NULL;
  
          if (mask == 0)
                  return 0;
  
          for (dce = driver_compats; dce->id != sentinel_id; dce++) {
                  if ((id & mask) == dce->id) {
                          if (matching_entryp != NULL) {
                                  *matching_entryp = dce;
                          }
                          return 1;
                  }
          }
          return 0;
  }
  
  /*
   * device_compatible_match_id:
   *
   *      Like device_compatible_match(), but takes a single
   *      unsigned integer device ID.
   */
  int
  device_compatible_match_id(
      uintptr_t const id, uintptr_t const sentinel_id,
      const struct device_compatible_entry *driver_compats)
  {
          return device_compatible_match_id_internal(id, (uintptr_t)-1,
              sentinel_id, driver_compats, NULL);
  }
  
  /*
   * device_compatible_lookup:
   *
   *      Look up and return the device_compatible_entry, using the
   *      same matching criteria used by device_compatible_match().
   */
  const struct device_compatible_entry *
  device_compatible_lookup(const char **device_compats, int ndevice_compats,
                           const struct device_compatible_entry *driver_compats)
  {
          const struct device_compatible_entry *dce;
  
          if (device_compatible_match_strarray_internal(device_compats,
              ndevice_compats, driver_compats, &dce, strarray_match)) {
                  return dce;
          }
          return NULL;
  }
  
  /*
   * device_compatible_plookup:
   *
   *      Look up and return the device_compatible_entry, using the
   *      same matching criteria used by device_compatible_pmatch().
   */
  const struct device_compatible_entry *
  device_compatible_plookup(const char **device_compats, int ndevice_compats,
                            const struct device_compatible_entry *driver_compats)
  {
          const struct device_compatible_entry *dce;
  
          if (device_compatible_match_strarray_internal(device_compats,
              ndevice_compats, driver_compats, &dce, strarray_pmatch)) {
                  return dce;
          }
          return NULL;
  }
  
  /*
   * device_compatible_lookup_strlist:
   *
   *      Like device_compatible_lookup(), but take the device
   *      "compatible" strings as an OpenFirmware-style string
   *      list.
   */
  const struct device_compatible_entry *
  device_compatible_lookup_strlist(
      const char * const device_compats, size_t const device_compatsize,
      const struct device_compatible_entry *driver_compats)
  {
          const struct device_compatible_entry *dce;
  
          if (device_compatible_match_strlist_internal(device_compats,
              device_compatsize, driver_compats, &dce, strlist_match)) {
                  return dce;
          }
          return NULL;
  }
  
  /*
   * device_compatible_plookup_strlist:
   *
   *      Like device_compatible_plookup(), but take the device
   *      "compatible" strings as an OpenFirmware-style string
   *      list.
   */
  const struct device_compatible_entry *
  device_compatible_plookup_strlist(
      const char * const device_compats, size_t const device_compatsize,
      const struct device_compatible_entry *driver_compats)
  {
          const struct device_compatible_entry *dce;
  
          if (device_compatible_match_strlist_internal(device_compats,
              device_compatsize, driver_compats, &dce, strlist_pmatch)) {
                  return dce;
          }
          return NULL;
  }
  
  /*
   * device_compatible_lookup_id:
   *
   *      Like device_compatible_lookup(), but takes a single
   *      unsigned integer device ID.
   */
  const struct device_compatible_entry *
  device_compatible_lookup_id(
      uintptr_t const id, uintptr_t const sentinel_id,
      const struct device_compatible_entry *driver_compats)
  {
          const struct device_compatible_entry *dce;
  
          if (device_compatible_match_id_internal(id, (uintptr_t)-1,
              sentinel_id, driver_compats, &dce)) {
                  return dce;
          }
          return NULL;
  }
  
  /*
   * Power management related functions.
   */
  
  bool
  device_pmf_is_registered(device_t dev)
  {
          return (dev->dv_flags & DVF_POWER_HANDLERS) != 0;
  }
  
  bool
  device_pmf_driver_suspend(device_t dev, const pmf_qual_t *qual)
  {
          if ((dev->dv_flags & DVF_DRIVER_SUSPENDED) != 0)
                  return true;
          if ((dev->dv_flags & DVF_CLASS_SUSPENDED) == 0)
                  return false;
          if (pmf_qual_depth(qual) <= DEVACT_LEVEL_DRIVER &&
              dev->dv_driver_suspend != NULL &&
              !(*dev->dv_driver_suspend)(dev, qual))
                  return false;
  
          dev->dv_flags |= DVF_DRIVER_SUSPENDED;
          return true;
  }
  
  bool
  device_pmf_driver_resume(device_t dev, const pmf_qual_t *qual)
  {
          if ((dev->dv_flags & DVF_DRIVER_SUSPENDED) == 0)
                  return true;
          if ((dev->dv_flags & DVF_BUS_SUSPENDED) != 0)
                  return false;
          if (pmf_qual_depth(qual) <= DEVACT_LEVEL_DRIVER &&
              dev->dv_driver_resume != NULL &&
              !(*dev->dv_driver_resume)(dev, qual))
                  return false;
  
          dev->dv_flags &= ~DVF_DRIVER_SUSPENDED;
          return true;
  }
  
  bool
  device_pmf_driver_shutdown(device_t dev, int how)
  {
  
          if (*dev->dv_driver_shutdown != NULL &&
              !(*dev->dv_driver_shutdown)(dev, how))
                  return false;
          return true;
  }
  
  void
  device_pmf_driver_register(device_t dev,
      bool (*suspend)(device_t, const pmf_qual_t *),
      bool (*resume)(device_t, const pmf_qual_t *),
      bool (*shutdown)(device_t, int))
  {
  
          dev->dv_driver_suspend = suspend;
          dev->dv_driver_resume = resume;
          dev->dv_driver_shutdown = shutdown;
          dev->dv_flags |= DVF_POWER_HANDLERS;
  }
  
  void
  device_pmf_driver_deregister(device_t dev)
  {
          device_lock_t dvl = device_getlock(dev);
  
          dev->dv_driver_suspend = NULL;
          dev->dv_driver_resume = NULL;
  
          mutex_enter(&dvl->dvl_mtx);
          dev->dv_flags &= ~DVF_POWER_HANDLERS;
          while (dvl->dvl_nlock > 0 || dvl->dvl_nwait > 0) {
                  /* Wake a thread that waits for the lock.  That
                   * thread will fail to acquire the lock, and then
                   * it will wake the next thread that waits for the
                   * lock, or else it will wake us.
                   */
                  cv_signal(&dvl->dvl_cv);
                  pmflock_debug(dev, __func__, __LINE__);
                  cv_wait(&dvl->dvl_cv, &dvl->dvl_mtx);
                  pmflock_debug(dev, __func__, __LINE__);
          }
          mutex_exit(&dvl->dvl_mtx);
  }
  
  void
  device_pmf_driver_child_register(device_t dev)
  {
          device_t parent = device_parent(dev);
  
          if (parent == NULL || parent->dv_driver_child_register == NULL)
                  return;
          (*parent->dv_driver_child_register)(dev);
  }
  
  void
  device_pmf_driver_set_child_register(device_t dev,
      void (*child_register)(device_t))
  {
          dev->dv_driver_child_register = child_register;
  }
  
  static void
  pmflock_debug(device_t dev, const char *func, int line)
  {
  #ifdef PMFLOCK_DEBUG
          device_lock_t dvl = device_getlock(dev);
          const char *curlwp_name;
  
          if (curlwp->l_name != NULL)
                  curlwp_name = curlwp->l_name;
          else
                  curlwp_name = curlwp->l_proc->p_comm;
  
          aprint_debug_dev(dev,
              "%s.%d, %s dvl_nlock %d dvl_nwait %d dv_flags %x\n", func, line,
              curlwp_name, dvl->dvl_nlock, dvl->dvl_nwait, dev->dv_flags);
  #endif  /* PMFLOCK_DEBUG */
  }
  
  static bool
  device_pmf_lock1(device_t dev)
  {
          device_lock_t dvl = device_getlock(dev);
  
          while (device_pmf_is_registered(dev) &&
              dvl->dvl_nlock > 0 && dvl->dvl_holder != curlwp) {
                  dvl->dvl_nwait++;
                  pmflock_debug(dev, __func__, __LINE__);
                  cv_wait(&dvl->dvl_cv, &dvl->dvl_mtx);
                  pmflock_debug(dev, __func__, __LINE__);
                  dvl->dvl_nwait--;
          }
          if (!device_pmf_is_registered(dev)) {
                  pmflock_debug(dev, __func__, __LINE__);
                  /* We could not acquire the lock, but some other thread may
                   * wait for it, also.  Wake that thread.
                   */
                  cv_signal(&dvl->dvl_cv);
                  return false;
          }
          dvl->dvl_nlock++;
          dvl->dvl_holder = curlwp;
          pmflock_debug(dev, __func__, __LINE__);
          return true;
  }
  
  bool
  device_pmf_lock(device_t dev)
  {
          bool rc;
          device_lock_t dvl = device_getlock(dev);
  
          mutex_enter(&dvl->dvl_mtx);
          rc = device_pmf_lock1(dev);
          mutex_exit(&dvl->dvl_mtx);
  
          return rc;
  }
  
  void
  device_pmf_unlock(device_t dev)
  {
          device_lock_t dvl = device_getlock(dev);
  
          KASSERT(dvl->dvl_nlock > 0);
          mutex_enter(&dvl->dvl_mtx);
          if (--dvl->dvl_nlock == 0)
                  dvl->dvl_holder = NULL;
          cv_signal(&dvl->dvl_cv);
          pmflock_debug(dev, __func__, __LINE__);
          mutex_exit(&dvl->dvl_mtx);
  }
  
  device_lock_t
  device_getlock(device_t dev)
  {
          return &dev->dv_lock;
  }
  
  void *
  device_pmf_bus_private(device_t dev)
  {
          return dev->dv_bus_private;
  }
  
  bool
  device_pmf_bus_suspend(device_t dev, const pmf_qual_t *qual)
  {
          if ((dev->dv_flags & DVF_BUS_SUSPENDED) != 0)
                  return true;
          if ((dev->dv_flags & DVF_CLASS_SUSPENDED) == 0 ||
              (dev->dv_flags & DVF_DRIVER_SUSPENDED) == 0)
                  return false;
          if (pmf_qual_depth(qual) <= DEVACT_LEVEL_BUS &&
              dev->dv_bus_suspend != NULL &&
              !(*dev->dv_bus_suspend)(dev, qual))
                  return false;
  
          dev->dv_flags |= DVF_BUS_SUSPENDED;
          return true;
  }
  
  bool
  device_pmf_bus_resume(device_t dev, const pmf_qual_t *qual)
  {
          if ((dev->dv_flags & DVF_BUS_SUSPENDED) == 0)
                  return true;
          if (pmf_qual_depth(qual) <= DEVACT_LEVEL_BUS &&
              dev->dv_bus_resume != NULL &&
              !(*dev->dv_bus_resume)(dev, qual))
                  return false;
  
          dev->dv_flags &= ~DVF_BUS_SUSPENDED;
          return true;
  }
  
  bool
  device_pmf_bus_shutdown(device_t dev, int how)
  {
  
          if (*dev->dv_bus_shutdown != NULL &&
              !(*dev->dv_bus_shutdown)(dev, how))
                  return false;
          return true;
  }
  
  void
  device_pmf_bus_register(device_t dev, void *priv,
      bool (*suspend)(device_t, const pmf_qual_t *),
      bool (*resume)(device_t, const pmf_qual_t *),
      bool (*shutdown)(device_t, int), void (*deregister)(device_t))
  {
          dev->dv_bus_private = priv;
          dev->dv_bus_resume = resume;
          dev->dv_bus_suspend = suspend;
          dev->dv_bus_shutdown = shutdown;
          dev->dv_bus_deregister = deregister;
  }
  
  void
  device_pmf_bus_deregister(device_t dev)
  {
          if (dev->dv_bus_deregister == NULL)
                  return;
          (*dev->dv_bus_deregister)(dev);
          dev->dv_bus_private = NULL;
          dev->dv_bus_suspend = NULL;
          dev->dv_bus_resume = NULL;
          dev->dv_bus_deregister = NULL;
  }
  
  void *
  device_pmf_class_private(device_t dev)
  {
          return dev->dv_class_private;
  }
  
  bool
  device_pmf_class_suspend(device_t dev, const pmf_qual_t *qual)
  {
          if ((dev->dv_flags & DVF_CLASS_SUSPENDED) != 0)
                  return true;
          if (pmf_qual_depth(qual) <= DEVACT_LEVEL_CLASS &&
              dev->dv_class_suspend != NULL &&
              !(*dev->dv_class_suspend)(dev, qual))
                  return false;
  
          dev->dv_flags |= DVF_CLASS_SUSPENDED;
          return true;
  }
  
  bool
  device_pmf_class_resume(device_t dev, const pmf_qual_t *qual)
  {
          if ((dev->dv_flags & DVF_CLASS_SUSPENDED) == 0)
                  return true;
          if ((dev->dv_flags & DVF_BUS_SUSPENDED) != 0 ||
              (dev->dv_flags & DVF_DRIVER_SUSPENDED) != 0)
                  return false;
          if (pmf_qual_depth(qual) <= DEVACT_LEVEL_CLASS &&
              dev->dv_class_resume != NULL &&
              !(*dev->dv_class_resume)(dev, qual))
                  return false;
  
          dev->dv_flags &= ~DVF_CLASS_SUSPENDED;
          return true;
  }
  
  void
  device_pmf_class_register(device_t dev, void *priv,
      bool (*suspend)(device_t, const pmf_qual_t *),
      bool (*resume)(device_t, const pmf_qual_t *),
      void (*deregister)(device_t))
  {
          dev->dv_class_private = priv;
          dev->dv_class_suspend = suspend;
          dev->dv_class_resume = resume;
          dev->dv_class_deregister = deregister;
  }
  
  void
  device_pmf_class_deregister(device_t dev)
  {
          if (dev->dv_class_deregister == NULL)
                  return;
          (*dev->dv_class_deregister)(dev);
          dev->dv_class_private = NULL;
          dev->dv_class_suspend = NULL;
          dev->dv_class_resume = NULL;
          dev->dv_class_deregister = NULL;
  }
  
  bool
  device_active(device_t dev, devactive_t type)
  {
          size_t i;
  
          if (dev->dv_activity_count == 0)
                  return false;
  
          for (i = 0; i < dev->dv_activity_count; ++i) {
                  if (dev->dv_activity_handlers[i] == NULL)
                          break;
                  (*dev->dv_activity_handlers[i])(dev, type);
          }
  
          return true;
  }
  
  bool
  device_active_register(device_t dev, void (*handler)(device_t, devactive_t))
  {
          void (**new_handlers)(device_t, devactive_t);
          void (**old_handlers)(device_t, devactive_t);
          size_t i, old_size, new_size;
          int s;
  
          old_handlers = dev->dv_activity_handlers;
          old_size = dev->dv_activity_count;
  
          KASSERT(old_size == 0 || old_handlers != NULL);
  
          for (i = 0; i < old_size; ++i) {
                  KASSERT(old_handlers[i] != handler);
                  if (old_handlers[i] == NULL) {
                          old_handlers[i] = handler;
                          return true;
                  }
          }
  
          new_size = old_size + 4;
          new_handlers = kmem_alloc(sizeof(void *) * new_size, KM_SLEEP);
  
          for (i = 0; i < old_size; ++i)
                  new_handlers[i] = old_handlers[i];
          new_handlers[old_size] = handler;
          for (i = old_size+1; i < new_size; ++i)
                  new_handlers[i] = NULL;
  
          s = splhigh();
          dev->dv_activity_count = new_size;
          dev->dv_activity_handlers = new_handlers;
          splx(s);
  
          if (old_size > 0)
                  kmem_free(old_handlers, sizeof(void *) * old_size);
  
          return true;
  }
  
  void
  device_active_deregister(device_t dev, void (*handler)(device_t, devactive_t))
  {
          void (**old_handlers)(device_t, devactive_t);
          size_t i, old_size;
          int s;
  
          old_handlers = dev->dv_activity_handlers;
          old_size = dev->dv_activity_count;
  
          for (i = 0; i < old_size; ++i) {
                  if (old_handlers[i] == handler)
                          break;
                  if (old_handlers[i] == NULL)
                          return; /* XXX panic? */
          }
  
          if (i == old_size)
                  return; /* XXX panic? */
  
          for (; i < old_size - 1; ++i) {
                  if ((old_handlers[i] = old_handlers[i + 1]) != NULL)
                          continue;
  
                  if (i == 0) {
                          s = splhigh();
                          dev->dv_activity_count = 0;
                          dev->dv_activity_handlers = NULL;
                          splx(s);
                          kmem_free(old_handlers, sizeof(void *) * old_size);
                  }
                  return;
          }
          old_handlers[i] = NULL;
  }
  
  /* Return true iff the device_t `dev' exists at generation `gen'. */
  static bool
  device_exists_at(device_t dv, devgen_t gen)
  {
          return (dv->dv_del_gen == 0 || dv->dv_del_gen > gen) &&
              dv->dv_add_gen <= gen;
  }
  
  static bool
  deviter_visits(const deviter_t *di, device_t dv)
  {
          return device_exists_at(dv, di->di_gen);
  }
  
  /*
   * Device Iteration
   *
   * deviter_t: a device iterator.  Holds state for a "walk" visiting
   *     each device_t's in the device tree.
   *
   * deviter_init(di, flags): initialize the device iterator `di'
   *     to "walk" the device tree.  deviter_next(di) will return
   *     the first device_t in the device tree, or NULL if there are
   *     no devices.
   *
   *     `flags' is one or more of DEVITER_F_RW, indicating that the
   *     caller intends to modify the device tree by calling
   *     config_detach(9) on devices in the order that the iterator
   *     returns them; DEVITER_F_ROOT_FIRST, asking for the devices
   *     nearest the "root" of the device tree to be returned, first;
   *     DEVITER_F_LEAVES_FIRST, asking for the devices furthest from
   *     the root of the device tree, first; and DEVITER_F_SHUTDOWN,
   *     indicating both that deviter_init() should not respect any
   *     locks on the device tree, and that deviter_next(di) may run
   *     in more than one LWP before the walk has finished.
   *
   *     Only one DEVITER_F_RW iterator may be in the device tree at
   *     once.
   *
   *     DEVITER_F_SHUTDOWN implies DEVITER_F_RW.
   *
   *     Results are undefined if the flags DEVITER_F_ROOT_FIRST and
   *     DEVITER_F_LEAVES_FIRST are used in combination.
   *
   * deviter_first(di, flags): initialize the device iterator `di'
   *     and return the first device_t in the device tree, or NULL
   *     if there are no devices.  The statement
   *
   *         dv = deviter_first(di);
   *
   *     is shorthand for
   *
   *         deviter_init(di);
   *         dv = deviter_next(di);
   *
   * deviter_next(di): return the next device_t in the device tree,
   *     or NULL if there are no more devices.  deviter_next(di)
   *     is undefined if `di' was not initialized with deviter_init() or
   *     deviter_first().
   *
   * deviter_release(di): stops iteration (subsequent calls to
   *     deviter_next() will return NULL), releases any locks and
   *     resources held by the device iterator.
   *
   * Device iteration does not return device_t's in any particular
   * order.  An iterator will never return the same device_t twice.
   * Device iteration is guaranteed to complete---i.e., if deviter_next(di)
   * is called repeatedly on the same `di', it will eventually return
   * NULL.  It is ok to attach/detach devices during device iteration.
   */
  void
  deviter_init(deviter_t *di, deviter_flags_t flags)
  {
          device_t dv;
  
          memset(di, 0, sizeof(*di));
  
          if ((flags & DEVITER_F_SHUTDOWN) != 0)
                  flags |= DEVITER_F_RW;
  
          mutex_enter(&alldevs_lock);
          if ((flags & DEVITER_F_RW) != 0)
                  alldevs_nwrite++;
          else
                  alldevs_nread++;
          di->di_gen = alldevs_gen++;
          di->di_flags = flags;
  
          switch (di->di_flags & (DEVITER_F_LEAVES_FIRST|DEVITER_F_ROOT_FIRST)) {
          case DEVITER_F_LEAVES_FIRST:
                  TAILQ_FOREACH(dv, &alldevs, dv_list) {
                          if (!deviter_visits(di, dv))
                                  continue;
                          di->di_curdepth = MAX(di->di_curdepth, dv->dv_depth);
                  }
                  break;
          case DEVITER_F_ROOT_FIRST:
                  TAILQ_FOREACH(dv, &alldevs, dv_list) {
                          if (!deviter_visits(di, dv))
                                  continue;
                          di->di_maxdepth = MAX(di->di_maxdepth, dv->dv_depth);
                  }
                  break;
          default:
                  break;
          }
  
          deviter_reinit(di);
          mutex_exit(&alldevs_lock);
  }
  
  static void
  deviter_reinit(deviter_t *di)
  {
  
          KASSERT(mutex_owned(&alldevs_lock));
          if ((di->di_flags & DEVITER_F_RW) != 0)
                  di->di_prev = TAILQ_LAST(&alldevs, devicelist);
          else
                  di->di_prev = TAILQ_FIRST(&alldevs);
  }
  
  device_t
  deviter_first(deviter_t *di, deviter_flags_t flags)
  {
  
          deviter_init(di, flags);
          return deviter_next(di);
  }
  
  static device_t
  deviter_next2(deviter_t *di)
  {
          device_t dv;
  
          KASSERT(mutex_owned(&alldevs_lock));
  
          dv = di->di_prev;
  
          if (dv == NULL)
                  return NULL;
  
          if ((di->di_flags & DEVITER_F_RW) != 0)
                  di->di_prev = TAILQ_PREV(dv, devicelist, dv_list);
          else
                  di->di_prev = TAILQ_NEXT(dv, dv_list);
  
          return dv;
  }
  
  static device_t
  deviter_next1(deviter_t *di)
  {
          device_t dv;
  
          KASSERT(mutex_owned(&alldevs_lock));
  
          do {
                  dv = deviter_next2(di);
          } while (dv != NULL && !deviter_visits(di, dv));
  
          return dv;
  }
  
  device_t
  deviter_next(deviter_t *di)
  {
          device_t dv = NULL;
  
          mutex_enter(&alldevs_lock);
          switch (di->di_flags & (DEVITER_F_LEAVES_FIRST|DEVITER_F_ROOT_FIRST)) {
          case 0:
                  dv = deviter_next1(di);
                  break;
          case DEVITER_F_LEAVES_FIRST:
                  while (di->di_curdepth >= 0) {
                          if ((dv = deviter_next1(di)) == NULL) {
                                  di->di_curdepth--;
                                  deviter_reinit(di);
                          } else if (dv->dv_depth == di->di_curdepth)
                                  break;
                  }
                  break;
          case DEVITER_F_ROOT_FIRST:
                  while (di->di_curdepth <= di->di_maxdepth) {
                          if ((dv = deviter_next1(di)) == NULL) {
                                  di->di_curdepth++;
                                  deviter_reinit(di);
                          } else if (dv->dv_depth == di->di_curdepth)
                                  break;
                  }
                  break;
          default:
                  break;
          }
          mutex_exit(&alldevs_lock);
  
          return dv;
  }
  
  void
  deviter_release(deviter_t *di)
  {
          bool rw = (di->di_flags & DEVITER_F_RW) != 0;
  
          mutex_enter(&alldevs_lock);
          if (rw)
                  --alldevs_nwrite;
          else
                  --alldevs_nread;
          /* XXX wake a garbage-collection thread */
          mutex_exit(&alldevs_lock);
  }
  
  const char *
  cfdata_ifattr(const struct cfdata *cf)
  {
          return cf->cf_pspec->cfp_iattr;
  }
  
  bool
  ifattr_match(const char *snull, const char *t)
  {
          return (snull == NULL) || strcmp(snull, t) == 0;
  }
  
  void
  null_childdetached(device_t self, device_t child)
  {
          /* do nothing */
  }
  
  static void
  sysctl_detach_setup(struct sysctllog **clog)
  {
  
          sysctl_createv(clog, 0, NULL, NULL,
                  CTLFLAG_PERMANENT | CTLFLAG_READWRITE,
                  CTLTYPE_BOOL, "detachall",
                  SYSCTL_DESCR("Detach all devices at shutdown"),
                  NULL, 0, &detachall, 0,
                  CTL_KERN, CTL_CREATE, CTL_EOL);
  }